British Prime Minister Boris Johnson refused to rule out putting England into a third national lockdown after Christmas.
Mr Johnson said he was "hoping to avoid" another shutdown but his remarks came as the country's R rate, which represents how many people each person carrying the virus infects, rose above 1.
The latest figure is estimated to be between 1.1 and 1.2, up from between 0.9 and 1 last week.
The premier admitted cases of coronavirus had increased "very much" in recent weeks.
When asked if the rest of the UK would follow Northern Ireland and Wales in introducing tougher measures, Mr Johnson said: “We’re hoping very much we will be able to avoid anything like that. But the reality is that the rates of infection have increased very much in recent weeks."
The prime minister is under pressure to tighten measures after doctors warned the relaxation of restrictions over Christmas will lead to a spike in cases and deaths.
Northern Ireland is due to start a six-week lockdown on December 26, and Wales is introducing tighter limits on household mixing two days later.
England currently has a regional approach to virus restrictions, with some areas facing stiffer rules than others. In Tier 3, the toughest level which will cover 68 per cent of England’s population from Saturday, bars, restaurants and indoor entertainment venues must close, but shops can remain open.
UK government scientist John Edmunds suggested the tier system was not working. "It doesn't look like the tier system is holding the epidemic wave back, unfortunately," he said. "I think we are going to have to look at these measures and perhaps tighten them up."
Latest data from the Office for National Statistics (ONS) published on Friday also showed a bleak picture, with the percentage of people testing positive for the virus rising in all four UK nations and a sharp increase in London.
Meanwhile, British retail sales fell last month after November's four-week lockdown in England closed non-essential shops.
Overall retail sales dropped 3.8 per cent on the month in November, their biggest decline since April when Britain was in lockdown, after a 1.3 per cent increase in October.
Annual sales growth halved to 2.4 per cent from 5.8 per cent, the ONS said, but many economists predicted a rapid recovery in December.
Since the Covid-19 outbreak, retail has been one of the few bright spots in Britain's economy, which the Bank of England (BoE) said has shrunk 11 per cent over the course of 2020, its biggest slump since 1709.
"Despite lockdowns across most of the UK, the level of spending is still higher than where it was in August and comfortably above its pre-virus level," ING economist James Smith said.
Consumer confidence showed its largest increase in eight years as households welcomed the availability of coronavirus vaccines, according to a monthly survey from market researchers GfK released on Friday.
The BoE expects the economy to shrink by just over 1 per cent in the final quarter of 2020, slightly less than forecast a month ago, but foresees major problems for early 2021 from longer-lasting lockdown restrictions.
Trading results have been mixed across retail with the online sectors booming and supermarkets recording solid sales, while many clothing retailers are struggling from their premises closing.
The 242-year-old department store chain Debenhams and Arcadia Group, which owns TopShop and other well-known brands, both announced severe financial difficulties last month, putting tens of thousands of jobs at risk.
Friday's data showed clothing sales down 19 per cent on the month, their biggest drop since April and almost a third lower than this time last year. Food sales rose by 3.1 per cent, the most since a wave of panic-buying in March.
Sales of fuel also fell, down 16.6 per cent on the month, as fewer people were driving. Online sales rose to 31.4 per cent of total spending, the highest since June.
"Feedback from stores is suggesting consumers brought forward their Christmas spending, particularly on festive home products and DIY," ONS deputy national statistician Jonathan Athow said.