According to The Sun, additional limits might come in as early as Boxing Day due to the rapid spread of Omicron.
Experts warn of hundreds of thousands of everyday infections.
The government's Boxing Day contingency plan has yet to be presented to ministers.
It comes after Government scientists stated UK hospital admissions with the variation are ‘probably approximately one tenth of the genuine number' due to reporting delays.
The Sage ‘situation update' on Thursday said it is ‘almost certain' that there are now hundreds of thousands of new Omicron infections per day in England.
Concerns about employee absences in key public services like the NHS, fire service, and police prompted London Mayor Sadiq Khan to declare a major incident.
After Christmas, the Government will ‘continue to look attentively at all data and keep our measures under review', a spokeswoman said.
While praising the present restrictions, Health Secretary Sajid Javid confessed he was conflicted about their introduction.
A delay in action earlier in the pandemic meant tougher and longer restrictions later, say experts.
To promote individual freedom and opportunity is one of the reasons I entered politics,' Mr Javid wrote in the Daily Telegraph.
‘But we must face the problem Omicron poses. In order to analyse the threat and create defences, we have been buying time.'
Last year, Boris Johnson's government declared Christmas a go before locking down.
Experts claim the move came too late, and within days, Covid was killing over 1,000 people each day.
Last week, Boris Johnson was defied by a huge number of Conservative backbenchers who voted against the mandatory use of Covid health cards for major venues.
Lord Frost, the Brexit minister who resigned on Saturday, stated in his letter that ‘we also need to learn to live with Covid, and I know that is also your inclination'.
Adding more limits may weaken Mr Johnson's grasp on power, causing substantial Tory dissatisfaction.
Given the recent revelations about Downing Street Christmas parties, post-Christmas limitations become more appealing.
But Stephen Reicher, a social psychologist at the University of St Andrews and a Sage member, warned that waiting until after Christmas was ‘probably too late'.
The UK Health Security Agency announced 10,059 new confirmed instances of the Omicron type of Covid-19 in the UK, bringing the total to 24,968 throughout the four nations.
But the genuine total is likely much higher.
In documents released on Saturday but dated December 8, the Scientific Pandemic Influenza Group on Modelling, Operational Sub-group (SPI-M-O) advised that a significant reduction in transmission ‘similar in scale to the national lockdown' of January this year would be required ‘to keep hospitalisations below previous peaks'.
A massive gathering might create several spreading events, experts warned.
Increasing the booster programme wouldn't help reduce hospital admissions, they claimed, because many people would be infected before immunity had built up.
‘We cannot allow the Prime Minister to sit on his hands while the NHS and businesses are on the brink of collapse,' said Liberal Democrat leader Sir Ed Davey.
On Saturday the Netherlands announced a complete shutdown.