Warning that the country was at a “tipping point”, Sir Keir asked Mr Johnson whether he would confirm reports that the Government was 80 per cent likely to back such a measure in the next two weeks.
The PM replied: “(Sir Keir) claims to be supporting the Government one day, and then performs a dramatic U-turn the next. Everybody can see what he’s doing…
“I rule out nothing, of course, in terms of combatting the virus.
“But we are going to do it with the local and regional approach that can and will drive down the virus if it is properly implemented.”
During the testy exchange, Sir Keir, who has urged the Government to impose the measure , accused Mr Johnson of rejecting the advice of his scientific advisers and urged him to go beyond his new three-tier alert level system to “save lives, fix testing and protect the NHS”.
A model by Sage scientists has suggested that thousands of deaths could be prevented by a short national lockdown over half-term. They argued that the coronavirus resurgence could be brought back under control by the so-called circuit-breaker that would buy ministers time to improve the test and trace system.
Sir Keir said he “couldn’t think of a single scientist” who backed Mr Johnson’s plan, with the government’s advisers describing tougher measures as “unavoidable”. He also defended his own calls for the shutdown, saying he had concluded it was “national interest” after reading the advice from experts.
“I know that for someone who has been an opportunist all his life this is difficult to understand, but having read and considered the Sage advice I have genuinely concluded that a circuit-break is in the national interest – genuinely concluded,” he said.
“It is the failure of the Prime Minister’s strategy that means tougher measures are now unavoidable. That is Sage’s view.”
Mr Johnson said he wanted to “avoid the misery of another national lockdown”. He said: “The plan is the plan that (Sir Keir) supported on Monday. And the whole point is to seize this moment now to avoid the misery of another national lockdown into which he wants to go head-long by delivering a regional solution.”
He also hit out at Labour’s “opportunism” and accused Sir Keir of performing a “dramatic” U-turn after not opposing the regional approach earlier in the week.
Sir Keir quipped that following the advice “is now apparently opportunistic”.
Mr Johnson also urged Labour’s metro mayors to support the Government’s new coronavirus restrictions, which includes a three-tier lockdown alert system .
The restrictions for England came into effect on Wednesday, but the Liverpool City Region is the only area to be under the toughest rules. Government health officials are expected to discuss with councillors in Greater Manchester and Lancashire whether to classify the areas as “very high” .
He told the Commons: “We want to put in the most stringent measures necessary in the places where the virus is surging in order to get it down where it surging, that is the logical thing to do. So will he get on to his Labour friends in those parts of the north of England where we want to work with them to put those very stringent measures in place in order to deliver the reductions that the whole country wants to see?”
Sir Keir accused the Prime Minister of being “behind the curve again”, adding: “He probably hasn’t noticed that this morning, the council leaders in Greater Manchester that he’s just quoted, including the mayor and including the Conservative leader of Bolton Council, have said in a press statement that they support a circuit-break above Tier 3 restrictions. Keep up Prime Minister.”