Boris Johnson has told MPs that "I rule out nothing" in the fight against coronavirus, but that he wants to "avoid the misery of another national lockdown".
The prime minister defended his three-tier system of local COVID-19 restrictions during a tempestuous PMQs clash with Labour leader Sir Keir Starmer.
It was their first encounter since Sir Keir came out in favour of a two to three-week "circuit breaker" coronavirus shutdown to coincide with October half-term.
Noting that the government's own scientific advisers had recommended such a course of action, the Labour leader asked: "Why did the prime minister reject that advice and abandon the science?"
Mr Johnson said he had been advised that a "regional approach" will "bring down the virus".
Justifying his new stance, Sir Keir told the Commons he had "genuinely concluded" that a short lockdown was "in the national interest".
"It is the failure of the prime minister's strategy that means tougher measures are now unavoidable," the Labour leader said, adding that the country was now at a "tipping point" and "time is running out".
The PM said he wanted to "seize this moment now to avoid the misery of another national lockdown into which he [Sir Keir] wants to go head-long by delivering a regional solution".
Mr Johnson added that "opportunism, I'm afraid, is the name of the game for the party opposite", accusing the Labour leader of "supporting the government one day" and performing a "dramatic U-turn the next".
"Everybody can see what he's doing. Labour have said it themselves, they see this as a good crisis for the Labour Party and one they wish to exploit - we see this as a national crisis that we are going to turn around," he said.
The PM added: "I rule out nothing, of course, in combating the virus but we're going to do it with the local, regional approach that can drive down and will drive down the virus if it is properly implemented."
With the devolved administrations able to introduce their own restrictions, Northern Ireland has announced that a four-week "circuit breaker" lockdown will come into force on Friday.
Welsh First Minister Mark Drakeford has told Sky News that his government is carrying out "detailed planning" for a potential second shutdown.
Nicola Sturgeon, the first minister of Scotland, has said she supports Mr Drakeford's call for a meeting of the government's emergency committee COBRA to "discuss collectively between the four nations what further steps we can all take at this stage to suppress the virus".
She is also advising people against travelling to hotspots in England after dozens of people who tested positive had recently visited Blackpool.
One of the PM's ministers had earlier played down the prospect of another national lockdown in England.
Asked if the country was heading for a national lockdown in the next two weeks, Work and Pensions Secretary Therese Coffey told Sky News: "I don't believe that is the case but as I say this will continue to be a decision that the prime minister will lead on."
The new system of coronavirus alert levels has split England into three different tiers - Tier 1 ("medium"), Tier 2 ("high") and Tier 3 ("very high").
It is designed to simplify the range of different restrictions already in place.
But local leaders have hit out at what they say is a lack of consultation about the new measures, as well as questioning the efficacy of some of the restrictions.
Health officials are expected to hold talks with councillors in Greater Manchester and Lancashire about potentially moving the areas to the "very high" alert level.
At the moment, the Liverpool City Region is the only area in this category.
Leaders in Greater Manchester have made clear that they will resist attempts to move the area from Tier 2 to Tier 3, describing the government's rationale as "fundamentally flawed".
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Geoff Driver, Conservative leader of Lancashire County Council, has said it is "inevitable" his region will move into Tier 3.
The PM urged Labour's metro mayors to support the government's strategy, telling 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."
"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," Mr Johnson said.
© Sky News 2020
