Get all the latest news on coronavirus and more delivered daily to your inbox. Sign up here.

As sunny and warm weather sent many outdoors and into parks in London over the weekend, the top health official in the U.K. warned Sunday that officials may go as far banning outdoor exercise if people still "flout the rules" to stop the spread of coronavirus.

Several parks in London were closed after the warmest weekend in six months sent thousands outdoors into parks on Saturday, with many pictured sunbathing and in large groups.

U.K. Health Secretary Matt Hancock said Sunday that sunbathing is against the guidance officials have set out to prevent the further spread of COVID-19 and that people need to follow the rules.

"The vast majority of people are following the public health advice, which is absolutely critical, and staying at home," he told Sky News. "But there are a small minority of people who are still not doing that -- it's quite unbelievable frankly to see that there are some people who are not following the advice."

UK CORONAVIRUS ADVISER SAYS LOCKDOWN MEASURES COULD BE EASED BY END OF MAY

Brockwell Park in London was forced to close Sunday after the local council announced that more than 3,000 people had gone there the previous day, many sunbathing and in large groups.

People observe social distancing as they pass by the locked gates to Brockwell Park in London after it was closed overnight to help stop the spread of coronavirus.

People observe social distancing as they pass by the locked gates to Brockwell Park in London after it was closed overnight to help stop the spread of coronavirus. (AP Photo/Matt Dunham)

Similar scenes were reported at Primrose Hill in Camden on Saturday when police said they were "disappointed" in how busy the park was.

Cyclists spread out as they observe social distancing whilst waiting at a traffic light by Regent's Park, London, as London's parks remain open with the warning that they will close if people fail to observe the British government guidelines.

Cyclists spread out as they observe social distancing whilst waiting at a traffic light by Regent's Park, London, as London's parks remain open with the warning that they will close if people fail to observe the British government guidelines. (AP Photo/Matt Dunham)

"We moved on 100+ people who we found with full picnics or blankets sunbathing or catching up with their friends!" police tweeted.

After police said they returned "a short while later," more crowds were discovered.

Hancock told the BBC on Sunday the government would "take action" if more steps are needed to keep large groups from congregating.

A dog walker wears a face mask in Regent's Park, London, as London's parks remain open with the warning that they will close if people fail to observe the British government guidelines that include two meters social distancing from people that don't live in the same household, to help stop the spread of coronavirus, Saturday, April 4, 2020. The new coronavirus causes mild or moderate symptoms for most people, but for some, especially older adults and people with existing health problems, it can cause more severe illness or death. (AP Photo/Matt Dunham)

A dog walker wears a face mask in Regent's Park, London, as London's parks remain open with the warning that they will close if people fail to observe the British government guidelines that include two meters social distancing from people that don't live in the same household, to help stop the spread of coronavirus, Saturday, April 4, 2020. The new coronavirus causes mild or moderate symptoms for most people, but for some, especially older adults and people with existing health problems, it can cause more severe illness or death. (AP Photo/Matt Dunham)

"If you don't want us to have to take the step to ban exercise of all forms outside of your own home, then you've got to follow the rules," he said Sunday.

The health secretary said most people are sticking to guidelines and that everyone should drive to "not have a minority spoil it for everybody."

CLICK HERE FOR FULL CORONAVIRUS COVERAGE

Restrictions in outdoor activities vary in Europe from country to country.

People walk near the beach during a nationwide confinement to prevent the spread of the coronavirus, in Biarritz, France, Saturday April 4, 2020.

People walk near the beach during a nationwide confinement to prevent the spread of the coronavirus, in Biarritz, France, Saturday April 4, 2020. (AP Photo/Bob Edme)

In Germany and Britain, residents can get out to exercise and walk their dogs, as well as go to the supermarket, the post office and other essential tasks. Yet in Serbia and South Africa, dog walking is not allowed.

Health officials announced an additional 621 deaths from the virus on Sunday in the country. There were at least 41,903 positive cases of COVID-19  in the U.K. and at least 4,934 deaths, according to Johns Hopkins University

In an address to the nation to be televised later Sunday, Queen Elizabeth II made an appeal for people to exercise self-discipline in “an increasingly challenging time," adding the pandemic brings daunting challenges to everybody.

It was only the fourth time since her reign began in 1953 that the 93-year-old queen has given such an address.

“I hope in the years to come everyone will be able to take pride in how they responded to this challenge,” she said in pre-released remarks. “And those who come after us will say that the Britons of this generation were as strong as any.”

CLICK HERE FOR THE FOX NEWS APP

British Prime Minister Boris Johnson as of Friday still had a fever, saying on Twitter he was "feeling better" after testing positive for COVID-19.

"I still have a temperature and so in accordance with government advice, I just continue my self-isolation until that symptom itself goes," he said Friday.

Johnson's infected pregnant fiancee, Carrie Symonds, tweeted she is “on the mend” after a week in bed.

"I haven’t needed to be tested and, after seven days of rest, I feel stronger and I’m on the mend," she said.

The Associated Press contributed to this report.