THE Prime Minister Boris Johnson is set to approve a four week delay to the planned June 21 reopening, in a blow to his roadmap out of lockdown.

Johnson had hoped to scrap all social distancing rules from a week on Monday in Step 4 of the roadmap, but a sharp rise in Covid cases caused by the Indian variant of the virus - now called Delta - has forced the PM to put the move on hold.

The Prime Minister is expected to agree to put the final easing of controls on hold for up to four weeks when he meets senior ministers and officials on his return on Sunday from the G7 summit in Cornwall.

It could mean that lockdown lifting – which had been slated for June 21 under the Government’s road map – will be put back to July 19.

The move, expected to be confirmed in a formal announcement on Monday, will be a bitter blow for many businesses, particularly in the hospitality sector, which had been pinning their hopes on a full summer reopening, as well as theatres, cinemas and sports grounds who were hoping to see the return of capacity crowds.

Mr Johnson is also likely to face opposition from some of his own MPs who have been chafing for months over the restrictions and will be furious at any further delay.

His government has also been repeatedly criticised for being too slow in acting to put India on the red travel list, allowing cases of the variant to enter the country freely.

Scientists have been pressing for additional time to get more people vaccinated – particularly those in younger age groups – before controls are relaxed.

Studies have shown that people who have received only one dose of the vaccine have significantly less protection against the Delta variant than those who have had two jabs.

Public health officials believe a delay would also give more opportunity to control the spread using surge-testing techniques which proved successful in Bolton, which was the first Delta variant hotspot.

Speaking in Cornwall on Saturday, a downbeat Mr Johnson acknowledged that the rise of the variant was a matter of “serious, serious concern”.

With infections and hospital admissions both rising, he said that it was not yet clear to what extent that would feed through into more deaths.

However, in order to ensure the final lockdown lifting was “irreversible”, he said that it may be necessary to give the vaccines “extra legs” in the race against the virus.

Some ministers however were reported to be even more pessimistic, with one telling The Sunday Telegraph that they had a “very short window” in which to open up, otherwise controls could have to stay in place until spring of next year.

“I am very worried the people who want to keep us shut down now want us to keep us shut down permanently and are aiming for ‘zero Covid’,” the unnamed minister was quoted as saying.

“Once you start delaying to the spring you’re making this type of control of people’s lives semi-permanent.”

Scientists now estimate that 96 per cent of all new cases of coronavirus are attributed to the Delta variant.

The latest figures from Public Health England (PHE) show there have been 42,323 cases of the Delta variant confirmed in the UK, up by 29,892 from the previous week.

It estimates the strain is 60 per cent more transmissible compared with the previously dominant Alpha, or Kent, variant, and that cases are doubling every four-and-a-half days in some parts of England.