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The public should not go sunbathing this bank holiday weekend despite reports that the coronavirus lockdown rules may be relaxed outdoors from Monday, Downing Street has urged.

No.10 insisted that people should stick to the current guidelines, but gave a strong hint that Boris Johnson would signal that more open-air activity was likely to be allowed in coming weeks.

Nearly seven weeks after the lockdown was imposed, government insiders have suggested that picnics, sunbathing, unlimited exercise and visits to outdoor cafes could all be included in the prime minister’s address to the nation at 7pm on Sunday night.

As Scottish first minister Nicola Sturgeon warned it would be a “potentially catastrophic mistake” to lift restrictions too early, Johnson told his cabinet that he would act with “maximum caution” in easing the rules and would “not hesitate” to tighten restrictions if needed again.

And in what appeared to be an attempt to reduce expectations following newspaper headlines, his spokesperson insisted no rules had been changed yet.

“In the light of some of the things I woke up to this morning, you will need to be very clear: any easement to the guidelines next week will be very limited.

“We are at a critical moment in the fight against the virus, and we will not do anything which was throwing away the efforts and sacrifices of the British public.”

With temperatures set to soar over the long weekend, and a Friday bank holiday to mark the 75th anniversary of VE Day, Downing Street scrambled to play down tabloid reports that some elements of life could return to normal as early as next week.

Asked directly if the public could sunbathe this weekend, the spokesperson said that as of today “there is no change to the advice, we are asking people to stay at home in order to stop the spread of the virus”.

Pressed again if people should “keep their clothes on” this weekend, they replied: “Yes absolutely. The social distancing measures we put in place are there for a reason and we would encourage everybody to continue doing what they have so far, to stick by the rules and help us protect the NHS.

“Those sacrifices have made a real difference in driving down the rate of transmission and we ask them to stick with them.”

However, No.10 also stressed that any changes would be based on the latest scientific advice and gave a strong hint of the areas for reform.

“What is the case because people like Professor Whitty have said at the daily press conferences is that there is evidence of a much reduced transmission outdoors compared to confined indoor spaces,” the spokesperson said.

Cabinet minister Brandon Lewis also tried to play down talk of “magic Monday” amid fears that abandoning the “stay home” slogan could lead the public to start thinking life could return to normal quicker than expected.

Johnson told the cabinet: “We are not going to do anything that risks a second peak. We will advance with maximum caution in order to protect the NHS and to save lives.

“We will be guided at every step by the science and the data. And we will closely track the impact of any easing of the social distancing measures and we will not hesitate to tighten the rules if required.”

His words follow reports that the government will jettison its “stay home, protect the NHS, save lives” slogan in favour of broader encouragement to “stay safe”.

As well as amending rules that restrict outdoor exercise to one hour, people may be able to visit outdoor cafes and markets, play golf and tennis and other non-contact sports, some newspapers have suggested.

But at her morning briefing, Sturgeon extended her lockdown for another three weeks.

“The other possible changes reported in the media today – such as encouraging more people back to work now or opening beer gardens or encouraging more use of public transport – would not, in my judgement, be safe for us to make yet.

“And I believe that for us to drop the clear, well understood ‘Stay at Home’ message right now could be a potentially catastrophic mistake.”