The British government on Sunday warned that outside exercise could be banned if people flout stringent guidelines to cut the spread of coronavirus infections.
The UK government on March 23 ordered a three-week shutdown of non-essential shops and services to cut close-contact transmission of the virus.
But warmer weekend weather has stoked fears that people could congregate in parks and open spaces, potentially threatening any gains made in cutting transmission rates.
A major south London park was closed on Sunday after concern about high numbers of sunbathers on Saturday.
Health secretary Matt Hancock, who himself tested positive for COVID-19, told Sky News television that sunbathing was "against the rules" and anyone doing so put lives at risk.
He told the BBC most people were following guidance only to leave their homes to shop for essential supplies and medicine, and to exercise once a day.
But he said it was "quite unbelievable" that a minority were not.
"The truth is the more people go out from home, the more the virus spreads," he added.
"I don't want to have to take away exercise as a reason to leave home because people are not following the rules...
"If the result of that is that too many people go out and flout the rules I'm afraid we'll have to take action."
Hancock later told a daily government briefing changes to social distancing rules were "not imminent".
- Medical officer rapped -
Meanwhile in Scotland, the country's chief medical officer apologised for ignoring her own advice about non-essential travel.
Police said they warned Catherine Calderwood for twice visiting her family's second home more than an hour from Edinburgh after photographs were published in a newspaper.
Chief constable Iain Livingstone of Police Scotland said officers "spoke to her about her action, reiterated crucial advice and issued a warning about her future conduct".
Calderwood, who fronts a public advertising campaign urging Scots to stay at home, told a news conference: "What I did was wrong. I'm very sorry. It will not happen again."
She added: "This was a mistake. Human error. And there's no excuses. I should not have done what I did."
Scotland's first minister Nicola Sturgeon said people's criticism and anger was justified, and she was right to apologise. But she backed her to remain rather than resign.
"She should not have got this wrong... But I need to have the best possible expertise... if we are to steer the best course through this," she added.
- Queen to speak -
The developments came as Britain reported 621 more deaths as of 1600 GMT on Saturday, taking the total toll to 4,934.
The toll -- down from a record day-on-day high of 708 as of Friday, after a week of steady increases -- includes a five-year-old child and seven healthcare workers.
There were 47,806 confirmed hospital cases as of 0800 GMT on Sunday, up 5,903 on the previous 24 hours.
Queen Elizabeth will make a rare special address at 1900 GMT on Sunday in which she is expected to praise people's response to the outbreak.
Her eldest son and heir, Prince Charles is recovering from mild symptoms of COVID-19.
Prime minister Boris Johnson remains in self-isolation with a high temperature after testing positive for the disease, which is expected to peak in Britain in the next week to 10 days.
His pregnant partner, Carrie Symonds, said she has also shown symptoms but not been tested.
