Boris Johnson has admitted that he is seriously concerned about the Indian Covid variant and will be “cautious” about lifting the final stage of lockdown.
With cases rising, the PM is expected to announce a delay to lockdown lifting in England of up to four weeks amid warnings the country is facing a third wave of the virus.
Asked by the BBC if all restrictions would now be lifted, Mr Johnson said people would have to wait until Monday to find out.
“What I can certainly say is we are looking at the data, continuing to do that, but what you can certainly take is… the roadmap was always cautious but irreversible, and in order to have an irreversible roadmap, we’ve got to be cautious,” he said.
Mr Johnson, who is currently hosting the G7 summit in Carbis Bay, Cornwall, added: “We made a massive progress with the vaccination programme - it’s done a huge amount of good - but you have got to be cautious to be irreversible.
“Again you have hospitalisations up, you’ve got cases up. There are grounds for caution. That doesn’t mean that this country hasn’t made enormous progress with vaccination.
“Clearly what we have is a race between the vaccines and the virus - and the vaccines are going to win. So it’s just a question of the pace.”
Mr Johnson also said that the spread of the Delta variant of the coronavirus is a matter of “serious, serious concern”.
He told Sky News: “It’s clear that the Indian variant is more transmissible and it’s also true that the cases are going up, and that the levels of hospitalisation are going up.
“Now, we don’t know exactly to what extent that is going to feed through into extra mortality, but clearly it’s a matter of serious, serious concern.”
Asked if he was less optimistic now than he was at the end of May, he said: “Yes, that’s certainly fair.”
It comes as a further 8,125 Covid-19 cases were announced by the government on Friday.
If unlocking is delayed reports suggest that a two-week review will be built into the plans meaning lockdown restrictions could be relaxed on July 5 if hospitalisations stay low.