Scientific advisers to the government have warned of the risk of lifting lockdown in England, as the UK heads into the weekend before rules change.
Professor John Edmunds said it was a “political decision” to ease measures; Sir Jeremy Farrar said the NHS test and trace system should be “fully working”.
More than two people will be able to meet outside from Monday and in England schools will reopen to some pupils.
Police have urged people not to break social distancing rules this weekend.
The Scientific Advisory Group for Emergencies (Sage), which advises the government, has published details of its confidential meetings.
It includes minutes of 34 Sage sessions, going back to 22 January, and a series of scientific reports.
They show one Sage meeting on 23 April estimated there would be only 1,000 cases per day by mid-May.
Instead, estimates by the Office for National Statistics suggest there are currently 8,000 cases per day in England alone. Those figures do not include cases in care homes or hospitals.
Prof Edmunds, from the London School of Tropical Hygiene and Medicine and a member of Sage, said the levels of the coronavirus were still “very high” and many scientists would rather the number of cases declined before measures were relaxed.
Sir Jeremy Farrar, director of the Wellcome Trust and a member of Sage, said on Twitter that Covid-19 is “spreading too fast to lift lockdown in England”, NHS test and trace had to be fully working and infection rates have to be lower.
The Sage documents warned there would be “little time” to re-impose stricter lockdown measures if the infection rate started to creep up again.
The documents also showed only half of people isolate for seven days when they become sick.
Papers revealed that Sage advice given to the Government in April said it was “likely” the infection rate – the R-number – would go above one (the point at which the epidemic starts to grow again) if non-essential shops were reopened.
It comes as police forces in England have warned people to take care in busy areas and beauty spots and as a fine weekend of weather is forecast.
From Monday, all four UK nations are due to have guidelines in place allowing more than two people to meet outside.
Each of the UK’s nations has a different approach – and timescale – to lifting lockdown. England is the only nation to reopen primary schools to selected year groups on Monday.
In Scotland, two separate households – up to a maximum of eight people – can meet outdoors and in Northern Ireland, groups of up to six people who do not live together can meet outdoors.
In Wales, any number of people from two different households will be able to meet each other outside from Monday, but beauty spots remain closed.
The warnings come as former prime minister Theresa May has written to her constituents saying Boris Johnson’s chief adviser Dominic Cummings did not “follow the spirit” of the lockdown guidance.
Mr Cummings drove more than 260 miles from London to County Durham with his wife who had coronavirus symptoms in March, at a time when the public was being told to “stay home”.
He also made a 50-mile round-trip to Barnard Castle 15 days later – a journey which police said might have broken lockdown rules.
Mrs May said in a letter to her constituents in Maidenhead, Berkshire, that she can “well understand the anger” of people who had obeyed the guidance.
On Friday, Chancellor Rishi Sunak set out how the UK’s coronavirus furlough scheme will finish at the end of October