As concern for the Delta coronavirus variant continues to grow across the country, there are fears that the easing of lockdown restrictions could be pushed back.

In the final stage of the government's roadmap out of lockdown, Boris Johnson said all restrictions would be lifted on June 21 in his "cautious but irreversible" plans.

However, there are now fears of a third wave due to a rise in cases of the highly transmissible Delta variant so those plans may need to change.

Ministers meet tomorrow to look at the data before making an expected announcement on Monday on whether it is safe to push ahead, the Mirror reports.

Here's a run-down of what lockdown options the Prime Minister has and how he will decide what to do.

Why are ministers worried about the Delta variant?

Cases of the Delta strain have more than doubled in a week, Public Health England has said.

The strain now accounts for more than 90% of new Covid cases across the country, after a further 29,892 infections were recorded in the seven days up to June 9 – up from 12,431 the week before.

The data also suggests the Delta variant has a 60% increased chance of spreading compared to the Alpha strain, first detected in Kent.

Labour Shadow Home Secretary Nick Thomas-Symonds has called the figures "deeply worrying" and Vaccines Minister Nadhim Zahawi has admitted England must be "really careful" about June 21.

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How will ministers decide on whether to delay 'Freedom Day'?

Four key tests must be met before ministers ease any more restrictions:

So, what are the lockdown options?

Mr Johnson could simply press ahead with the June 21 easing of all restrictions planned for step four.

Those include:

But it seems increasingly unlikely that all these changes will go ahead at once, on time.

Reports have said the PM is eyeing a delay of up to four weeks to July 19, with a two-week review that would allow for restrictions to be dropped on July 5 if hospitalisations stay low.

However, Cabinet sources told the Daily Mail that 'Freedom Day' on June 21 was "not looking great", and a four-week delay was now "most likely".

Alternatively, the government could take a "mix and match" approach to lifting curbs, such as allowing unlimited numbers of people at weddings but keep face masks mandatory beyond June 21.

This was warned of way back in February's roadmap, which said: "Some measures may be required even after all adults have been offered a vaccine."

What about vaccine passports?

Ministers had said vaccine passports - not to be confused with those needed for international travel - which allows people to prove they have been jabbed could see curbs lifted safely.

The idea was that pub landlords or stewards at large events could insist on seeing them before letting people in.

But amid fears the certificates will hit civil liberties and potentially see workers and punters discriminated against, they are likely to be ruled out as part of the review.

Cabinet Office minister Michael Gove recently cast doubt on the plan, telling MPs the "judgement is finely balanced" and it was wrong to assume ministers will push ahead "come hell or high water".

"We've been looking at it pragmatically, to see if it can add value, and if not, then we would not press ahead with it," he said.

Separately, Labour MPs and a slew of Tory backbenchers have underlined they will fight domestic vaccine passports in the Commons.