Watch: Scientists agree Manchester and Lancashire should go into Tier 3 lockdown
A decision on whether Tier 3 lockdown restrictions should be imposed on Greater Manchester and Lancashire could be made tomorrow, Sky News understands.
Advisers on the Joint Biosecurity Centre's "Gold command" taskforce have signed off on the proposals.
But to be implemented, the measures would need to be signed off by the prime minister.
Andy Burnham, the mayor of Greater Manchester, said the government had not made him aware of the move.
He said in a tweet: "At no point during tonight's briefing was this news communicated to us. Media told first once again. Our position has not changed."
Mr Burnham has vowed to consider legal action if the strictest tier of coronavirus restrictions is imposed on the region.
He said in an online news conference that if any such action was taken it would be "by imposition, not consent" and that he would "not cave into the pressure" by agreeing to the restrictions.
Mr Burnham has been in meetings with the deputy chief medical officer today and has tweeted to say he is expecting another meeting with Boris Johnson's team in the morning.
Under the government's new rules, people living in Tier 3 areas would be banned from socialising with other households both indoors and in private gardens, while bars and pubs would be closed unless they can operate as restaurants only.
Geoff Driver, the Conservative leader of Lancashire County Council, said earlier it was "inevitable" his region would enter Tier 3.
Manchester and Lancashire are facing tighter restrictions after Mr Johnson insisted he wanted to avoid the "misery" of another national lockdown.
Chancellor Rishi Sunak has warned it would cause "significant damage" to livelihoods.
The prime minister has clashed with Sir Keir Starmer over the Labour leader's call for a short "circuit breaker" lockdown aimed at getting the virus back under control.
Leading scientists have suggested that a short lockdown, possibly over Christmas, could prevent the NHS being overwhelmed and potentially reduce the death toll this winter.
Watch: Matt Hancock ‘concerned’ as daily UK Covid-19 cases hit highest level
The row over England's approach to tackling a surge in coronavirus cases came as:
Welsh First Minister Mark Drakeford set out plans to ban travel into the country from high-risk areas of England, Scotland and Northern Ireland from 6pm on Friday
Nicola Sturgeon advised Scots against travelling to English coronavirus hotspots, singling out Blackpool as "associated with a large and growing number of COVID cases in Scotland"
Northern Ireland's First Minister Arlene Foster announced that pubs and restaurants will close for four weeks - with the exception of takeaways and deliveries - while schools will close on Monday for two weeks, one of which will cover the half-term break
The Republic of Ireland has agreed a ban on all household visits across the country from tomorrow night - with the exception of visits made on compassionate grounds or essential reasons
The latest figures showed 19,724 more lab-confirmed cases of coronavirus in the UK and that a further 137 people have died within 28 days of testing positive for COVID-19.
Pressure on the prime minister to take tougher action has intensified after Sir Keir backed the call from the Scientific Advisory Group for Emergencies (SAGE) for a short national lockdown.
SAGE advises the government on its response to the coronavirus.
In testy exchanges at Prime Minister's Questions, Mr Johnson accused him of opportunism and urged the Labour chief to put pressure on his party's local leaders in northern England to accept tighter restrictions under the new multi-tier system.
Sir Keir's call for a lockdown has fractured the fragile consensus on the coronavirus response that existed at Westminster, and in the Commons he suggested the prime minister's failure to follow scientific advice had cost lives.
Watch: Can you catch coronavirus twice?