With the new strain of coronavirus reported to have spread across the UK, ministers are said to be considering a third national lockdown from Boxing Day.
Genomic researchers have found the new variant, which is said to be 70% more infectious than previous strains, in England, Wales and Scotland.
The Cabinet are understood to have previously discussed plunging the whole country into the highest Tier 4 restrictions when it met on Saturday.
However, a source told The Mirror that the decision may yet be taken to go for a full lockdown rather than the regional tier system currently in place.
The source told the paper: “The situation is developing quickly so we need to respond at the same pace.”
Commenting on the reports, housing and communities secretary Robert Jenrick said there is no “immediate plan” to widen coronavirus restrictions on Boxing Day.
But Jenrick told BBC Breakfast that the government would be meeting today to review the situation and “make a judgement”.
He said: “We don’t have an immediate plan to take action, but the number of cases is rising and the [new coronavirus] variant is spreading to other parts of the country, so we will see whether it’s necessary to do more and make sure that the tiered system is sufficiently robust for the new circumstances.
“Because remember, the tiered system was designed before we knew the full ferocity of the new variant, and so we do have to make sure it’s sufficiently robust to be able to withstand this and to stop cases just rising at the very worrying levels they are now in parts of the country.”
Labour leader Sir Keir Starmer has written to Boris Johnson to say his party would back any government moves to tighten restrictions if that is what scientists recommend.
Watch: How England's coronavirus restrictions work