Staying at home this weekend is an instruction and "not a request", Health Secretary Matt Hancock said as he updated the country on the coronavirus.
Speaking at the No 10 briefing, Mr Hancock said that while warm weather was forecast in some areas this weekend "the disease is still spreading".
Meanwhile, England's chief nursing officer Ruth May paid tribute to two nurses who have died from the disease.
"Please stay at home for them," she urged people.
Areema Nasreen, 36,
had spent weeks in intensive care with coronavirus, while Aimee O'Rourke, 39,
died at the hospital where she worked.
"They were one of us, they were one of my profession, of the NHS family," said Ms May. "I worry that there's going to be more and I want to honour them today and recognise their service."
It comes as latest figures showed a further 684 people with the virus died in the UK, bringing the total to 3,605. There are 38,168 confirmed cases.
In Scotland, the number of deaths has risen by 46, while in Wales a further 24 people died. In NI, the number of people who died with coronavirus has risen by 12.
Mr Hancock - who had recently ended his seven days of self-isolation after contracting the virus - said: "We cannot relax our discipline now. If we do, people will die.
"I end with the advice we all know. This advice is not a request - it is an instruction.
"Stay at home, protect lives and then you will be doing your part."
The warning follows messages from
local councils, tourism bosses and police urging people to stay away from beauty spots, as the Easter holidays begin and warm weather is expected.
Mr Hancock also said the UK has set up three national clinical trials looking at how existing drugs can be altered to treat Covid-19.
He added that more patients are needed to volunteer to take part in the trials - but England's deputy chief medical officer later clarified that people cannot apply themselves and it was up to doctors to refer patients.
https://www.bbc.co.uk/news/uk-52155430