"Of course if we get into a situation where it's unacceptable and we do need to put back further restrictions, then that of course is something the government will look at," Ms. Lucy Frazer, a government minister, told Sky News on Friday.
The remarks from Ms. Frazer, the government's solicitor general, are the most explicit yet that UK Prime Minister Boris Johnson's stated wish for the current unlocking to be "irreversible" may be confounded by the progression of the virus.
The UK reported 48,553 new coronavirus cases on Thursday and the number of people in hospital rose 42.8 per cent in a week, Bloomberg reported.
The wave of infections from the highly transmissible Delta variant is now causing staffing problems for some British employers.
Latest figures showed 520,000 people were told to self-isolate with a notification from the National Health Service Covid-19 app, which tracks contacts of people who have been close to patients who test positive for the virus.
On Monday, the government will allow nightclubs to open for the first time in 16 months and drop remaining Covid-19 rules including limits on gatherings indoors and outdoors, the requirement to wear face masks in shops and on trains, and the guidance for people to work from home if able.
With infection rates rising amid the spread of the Delta variant, Chief Medical Officer Chris Whitty warned that the UK isn't "out of the woods yet".
He said: "I don't think we should underestimate that we could get into trouble again, surprisingly fast."