Ministers are considering pushing back the relaxing of restrictions originally planned for 21 June for up to four weeks.
A final decision is expected to be made on Sunday, ahead of a formal announcement by Johnson at a news conference the following day.
‘Substantial’ third wave
The news comes as repeated warnings from scientists say that the rapid spread of the Delta variant could lead to a “substantial” third wave if controls are lifted.
Doctors in the British Medical Association (BMA) joined calls on Friday for the final lifting of restrictions to be put on hold in order to enable millions more to gain the protection of the vaccine.
BMA council chairman Dr Chaand Nagpaul said: “When only 54.2 per cent of the adult population currently fully vaccinated, and many younger people not yet eligible, there is a huge risk that prematurely relaxing all restrictions will undo the excellent work of the vaccine programme and lead to a surge of infections.
“It’s not just about the number of hospitalisations, but also the risk to the health of large numbers of younger people, who can suffer long term symptoms affecting their lives and ability to work.”
‘A huge blow for families and businesses’
A delay until possibly 19 July would be a blow to many businesses, particularly those in the hospitality and leisure sectors.
Labour shadow home secretary Nick Thomas-Symonds said that the country was not paying the price for the refusal of ministers to heed the warnings of its own Scientific Advisory Group for Emergencies (SAGE).
He said: “Any delay in rolling back restrictions would be a huge blow for many families and businesses across the country. The fault for this lies squarely with Conservative ministers.
“Despite warnings from Labour, Sage and others they continued with a reckless border policy that allowed the Delta variant to reach the UK and spread.
“Now British people look set to have to pay the price.”
Delta variant more transmissible
It is estimated by scientists that 96 per cent of all new cases of Covid-19 are attributed to the Delta variant.
The latest figures from Public Health England (PHE) showed that there have been 42,323 cases of the Delta variant confirmed in the UK, up by 29,892 from the previous week.
The figures estimate that the strain is 60 per cent more transmissible compared with the previously dominant Alpha variant, and that cases are doubling every four and a half days in some areas in England.
Additional reporting by PA.