Chaos continued at Heathrow today as passengers faced long queues at border control with no social distancing and red arrivals 'stood an arm's length from other travellers'.
Pictures from last night showed snaking queues with bored passengers packed tightly together - with the crowd at one point bursting into a rendition of 'Take Me Home, Country Roads' to pass the time.
One passenger who came through Terminal 2 last night told MailOnline it took them three hours to get through the border, and claimed there were just three immigration officers checking documents by the e-gates and four manned passport desks.
Travellers also complained of chaos today, with Farah, a surgeon, tweeting: 'TWO HOURS & FIFTY MINUTES *standing* in line at passport control. How is this acceptable?'
Pictures from last night showed snaking queues with bored passengers packed tightly together
Another photo taken at Heathrow last night as passengers continued to see long queues
One passenger tweeted: 'I'm in a coronavirus factory!! It's called HeathrowAirport arrivals'
Meanwhile, another passenger tweeted: 'I'm in a coronavirus factory!! It's called HeathrowAirport arrivals.'
He later said: 'You've got a queue of people from red list countries, standing no more than an arm's length away, from a queue of people entering from other ''non- red'' countries. Who's the floor manager? Give him a raise!'
Holidays are currently banned but some people still need to travel for vital reasons such as work or to attend a funeral. All arrivals in Britain must have a negative Covid test and wear a mask while at the airport.
Arrivals on the 'red list' of high-risk countries, such as Brazil and Portugal, have to stay in a quarantine hotel for 10 days.
A passenger who came through Terminal 2 last night told MailOnline: 'There were at least three times the amount of passenger as there were a month ago.
'It was completely impossible to social distance and they had airport staff just stood about.'
Travellers also complained of chaos today, with Farah, a surgeon, complaining to Heathrow
What are the rules for entering Britain?
Checking passports at the border is the responsibility of the Home Office, while enforcing social distancing and mask wearing within the airport is down to the Heathrow authorities.
On Sunday, arrivals at Britain's largest airport told how they waited between five and seven hours with little social distancing.
The Home Office said Sunday's backlogs were due to travellers arriving without having booked their testing package ahead of travel into the UK, meaning border officials were overstretched.
Under the rules, arrivals from safe countries who are not subject to hotel quarantine have to purchase a testing package online before flying.
It comes with two tests, to be taken on the second and eighth days of self-isolation at home.
Aura Radu, 24, arrived on a flight from Romania at 6pm on Sunday but did clear passport control until just after midnight.
She said: 'It was like hell on earth. Hundreds of us were made to wait for more than six hours and when we asked security staff what was going on, they just shrugged their shoulders. It was horrendous.
'We had no food, and it became very hot and a lot of passengers like me almost fainted. We pleaded with officials to give us some water, which they eventually did.
'There were passengers from red list countries and others who were not, all mixing together. It was complete chaos, an utter shambles.'
A Heathrow spokesperson said: 'When additional measures were implemented at the border, we were clear with the Government that they must support the Border Force to ensure appropriate numbers of officials are on duty to minimise queuing in the Immigration Hall.
'It is deeply regrettable that Border Force has been unable to provide adequate resourcing, despite our many attempts to highlight the implications of not doing so.
'Leaving arriving passengers to queue for hours is unreasonable and no airport has the space to hold arriving passengers in socially distanced queues for over four hours, as has been the case in recent weeks.'
MailOnline the Home Office for comment.
Sunday - Passengers were left furious as they waited more than six hours to pass through border checks
It comes as police revealed that a man and a woman have been issued with £10,000 fines for failing to go into hotel quarantine after returning from Dubai.
33 'high-risk' nations from which arriving travellers will have to quarantine in hotels
Democratic Republic of the Congo
Portugal (including Madeira and the Azores)
United Arab Emirates (UAE)
Merseyside Police said fixed penalty notices for failing to comply with travel regulations were issued to two people from the Wirral after they avoided a direct flight back from the country, which is currently on the foreign travel red list, to one of the specified ports of entry required for quarantine.
A force spokesman said they received a report of rule-breaking last Tuesday.
Following an investigation, both were issued on with a £10,000 fine on Friday and transported to a designated quarantine hotel.
Chief Inspector Chris Barnes said: 'Strict rules around international travel have been put in place by the Government for a reason, and to disregard them in this way is selfish, inconsiderate, and potentially dangerous.
'Currently, the regulations mean that if you are a British or Irish national, or you have residence rights in the UK and are returning from a country on the foreign travel red list, you must quarantine in a Government-approved hotel for 10 days.
'If you are required to quarantine at a hotel, you can only arrive in England at certain ports of entry.
'In this instance, the pair in question avoided a direct flight route back from Dubai to one of the specified airports in an attempt to evade this process.
'However, this was ultimately unsuccessful and has now resulted in a significant fine of £10,000 each.
'I hope this incident sends out a clear message to anyone considering breaching travel regulations in this way that we will not tolerate it, and you will be dealt with robustly.
'We are at a crucial point in the pandemic and it's vital that everyone continues to abide by the restrictions so that we can meet the criteria needed for lockdown to ease.
'By not doing so, you are not only jeopardising this process, but recklessly putting your health and the health of others at risk.'
Missing patient who tested positive for Brazil variant STILL has not been found, ministers admit, as it emerges mutant strain is in '15 countries not on the "red list"'
By Jack Maidment, Deputy Political Editor for MailOnline
Ministers today admitted they are still searching for the unidentified sixth case of the Brazilian coronavirus variant in the UK as it emerged the strain has been identified in at least 15 countries not on the travel 'red list'.
Business Secretary Kwasi Kwarteng this morning confirmed the person is yet to be found as he said 'we are still trying to work out exactly what has happened to that potential carrier'.
Mr Kwarteng said the Government is 'still monitoring the situation very closely' as it scrambles to stop the variant from spreading.
The strain, first discovered in the Brazilian city of Manaus, has spooked experts and ministers because it has mutations which are thought to increase transmissibility.
There are also concerns that the variant can re-infect people who have previously had Covid and that it has the ability to lessen the impact of vaccines.
The Government has deployed surge testing in South Gloucestershire after two cases of the variant were identified there
WHAT DO WE KNOW ABOUT THE BRAZIL VARIANT?
Date: Discovered in Tokyo, Japan, in four travellers arriving from Manaus, Brazil, on January 2.
Why should we care? The variant has the same spike protein mutation as the highly transmissible versions found in Kent and South Africa - named N501Y - which makes the spike better able to bind to receptors inside the body.
It has a third, less well-studied mutation called K417T, and the ramifications of this are still being researched.
What do the mutations do?
The N501Y mutation makes the spike protein better at binding to receptors in people's bodies and therefore makes the virus more infectious.
Exactly how much more infectious it is remains to be seen, but scientists estimate the similar-looking variant in the UK is around 56 per cent more transmissible than its predecessor.
Even if the virus doesn't appear to be more dangerous, its ability to spread faster and cause more infections will inevitably lead to a higher death rate.
Another key mutation in the variant, named E484K, is also on the spike protein and is present in the South African variant.
E484K may be associated with an ability to evade parts of the immune system called antibodies, researchers from the Federal University of Rio de Janeiro said in a scientific paper published online.
However, there are multiple immune cells and substances involved in the destruction of coronavirus when it gets into the body so this may not translate to a difference in how people get infected or recover.
Do our vaccines work against it?
There are concerns that vaccines might be less effective against the Brazilian strain, with trials of the Johnson & Johnson jab finding it was slightly less effective in Latin America at preventing mild or moderate cases.
However, the trials found it still prevented hospitalisations and deaths.
No studies have tested the Oxford/AstraZeneca vaccine against the P1 variant, while Moderna and Pfizer say their mRNA coronavirus vaccines should work against variants with the E484K mutation, with early results showing that these vaccines are only slightly less effective against the P1 variant.
The discovery of the six cases in the UK has prompted criticism of the Government's hotel quarantine policy, with Labour arguing it is not strict enough.
Calls for the system to be toughened up are likely to grow after it emerged the concerning strain has been identified in at least 15 countries not on the 'red list'.
The Guardian reported that a list of verified cases compiled by the World Health Organisation includes the US, Canada, France, Germany, Spain and Japan.
The Government's 'red list' policy in England currently bans travel from more than 30 countries which have had variant outbreaks.
UK citizens can still come back from those countries but they must spend 10 days in a quarantine hotel.
Travellers returning from non-'red list' countries must self-isolate for 10 days at home.
Labour has repeatedly called for the policy to be strengthened, arguing the Government's border measures are always 'too little, too late'.
Health Secretary Matt Hancock last night defended the border arrangements as he argued that home quarantine measures were already in place and travel restrictions on Brazil had been imposed before the hotel policy was implemented.
Mr Kwarteng was asked during an appearance on Sky News whether the sixth case had been found.
He replied: 'I think we are still monitoring the situation very closely and you are quite right, I think there was one case of the Brazilian variant, as far as I know there are six cases, but there is one where the person involved didn't fill in the forms correctly and we are still trying to work out exactly what has happened to that potential carrier.
'But we are dealing with this situation and I would like to remind you also that we have the South African variant and we have been dealing with that too.'
The missing person is thought to have been tested on February 12 or 13, possibly via a home postal test or a test collected from a local authority.
In total, Public Health England has identified six UK cases of the concerning so-called P1 variant – three in England and three in Scotland.
Three cases are Scottish residents who flew to Aberdeen from Brazil via Paris and London, who all tested positive while self-isolating.
Other passengers who were on the same flight to Aberdeen are now being traced.
The other two cases in England are from the same household in South Gloucestershire after one person returned from Brazil on February 10 – just days before the Government's hotel quarantine rule came into force.
Two other people in the same household have also tested positive but are not currently included in the UK case total of six, while tests on their type of coronavirus continue.
Officials are searching for passengers who were on the Swiss Air flight LX318 from Sao Paulo to Heathrow, via Zurich, which landed on February 10.
Surge testing will now be carried out in the Bradley Stoke, Patchway and Little Stoke areas of South Gloucestershire to capture any potential spread in cases.
Labour leader Sir Keir Starmer said the discovery of the variant in the UK showed the Government had not 'secured our borders in the way we should have done'.
Vaccines minister Nadhim Zahawi said any community transmission of the variant would be identified 'very, very quickly' through both regular PCR and lateral flow testing.