ICELAND, Denmark or Cyprus could be next on the UK's quarantine list if cases continue to rise - after Grant Shapps revealed the threshold for changing travel advice.
Last night France's cases per 100,000 over the last seven days crept over the 20 mark - forcing it onto the unsafe list.
The country had seen a 66 per cent hike in cases in the last week, forcing the Government to act. Malta and the Netherlands have also been removed from the quarantine-free safe travel list.
Anyone has to quarantine for two weeks if they arrive back in the UK after 4am on Saturday.
But with flights fully booked and the Channel Tunnel packed, many will miss the deadline.
Around 160,000 Brits are thought to be in France at the moment, the Government says.
Transport Secretary Mr Shapps told Radio 4 this morning: "In France the numbers have just got above the threshold, which is about 20 cases per 100k but measured on a 7 day average."
What we know so far:
The move has sparked a huge rush of tourists hoping to make it back into the UK before the deadline.
P&O ferries said it had seen 8,000 people looking at their website today for bookings back to the UK from France.
But Mr Shapps warned people not to show up at ports trying to secure a seat.
"The advice from all the travel operators is very clear: to contact them in advance. Don't just turn up," he said.
"Because you'll almost certainly be disappointed and it will just create queues, which no one wants to see."
He said tourists should not be "entirely surprised" at the changes - as the Government had warned it may happen.
"I think given what's happened this summer, given what's already happened in places like Spain and the vast amount of coverage about concerns in France and elsewhere, no one will be entirely surprised," he added.
"But I do sympathise with people. As I say, I've been there myself and ended up having to quarantine as a result."
The Government has said they will keep the travel advice for all countries under constant review, and will look at the cases regularly to decide whether to make chances.
Iceland is on 31.1 cases per 100,000 over a two week period according to the European Centre for Disease Prevention and Control - just below France on 32.1 - and may be the next country be added.
Demark has 24.7 cases per 100k, Poland has 24.4 and Cyprus has 24.1.
In comparison, the UK has 18.5 per 100,000 over the last two weeks of data.
Brits were in a scramble to get back today if they could.
Nurse Helen Gandy in France told the BBC: "When we left the infection rates were low, now we are worrying we are going to have to quarantine when we get back.
"We are about 8.5 hours from Calais, right in the south. We have a shuttle booked. We are hoping we might be able to get onto an earlier crossing. that is adding to the stress as well.
"We are just hours away from the 4am cut off, which is frustrating."
Ian, who has been in France since August 7, dashed to his computer to secure return tickets back to the Uk as soon as he heard the news last night.
He said: "Immediately we saw France added to the list, we got onto the internet on three computers on various booking sites, we have been very lucky and got a ferry crossing from Dunkirk."
Boris Johnson said yesterday that he had to be “absolutely ruthless” over imposing the travel rules, “even with our closest and dearest friends and partners”.
Seats on a British Airways flight from Paris' Charles De Gaulle airport to Heathrow on Friday quadrupled in price - from £100 to £407 - after the Government's announcement.
Channel Tunnel operator Getlink said extra services may be laid on but warned many passengers face missing out on the quarantine deadline.
John Keefe, Getlink's director of public affairs, told BBC Newsnight the trains were "already pretty much fully booked" today.