Staying two metres apart will still be key to keeping many people safe as the lockdown rules are slightly eased, the country’s coronavirus experts said.

There have been calls to change social-distancing rules to reduce the minimum distance people should stay apart to one metre, including from the hospitality sector to allow pubs to reopen.

But England’s chief medical officer Professor Chris Whitty, and the Government’s chief scientific adviser, Sir Patrick Vallance, both suggested two metres was still necessary as the risk of spreading the virus remained too great.

It came as Prime Minister Boris Johnson said groups of up to six people are to be allowed to meet outside, provided those from different households “continue strictly to observe social-distancing rules” by staying two metres apart.

On questions about reducing social distancing, Sir Patrick Vallance said: “It’s not an absolute (that) beyond two metres is safe and slightly less is not safe, there’s a graduation across that, and so roughly at a metre it’s somewhere between 10 and 30 times more risky than at two metres.”

Professor Whitty said it was “really important” that people stayed two metres apart when meeting outside, adding they would not be counted as a contact, and therefore would not need to self-isolate if someone they met at a distance then developed coronavirus.

Prof Whitty, who said that keeping the distance will ensure the risk is low, added: “If you do maintain two metres distance and the contacts you’ve had turn out subsequently to have coronavirus, you will not be counted as a contact and you will not have to self-isolate.

“On the other hand, if you don’t, then if they get coronavirus then a) you might get it and b) because you might have got it, it’s likely that you’ll have to self-isolate.”

Mr Johnson agreed with his advisers and added: “I must stress that to control the virus, everyone needs to stay alert, act responsibly, strictly observe social distancing rules, and stay two metres apart from those who you do not live with.

“Minimising contact with others is still the best way to prevent transmission.”

Everyone was urged to try to avoid seeing people from too many households in quick succession, in an effort to limit the risk of quick transmission from lots of different families and to control the spread of the virus.

Speaking to the PA news agency on Thursday, Emma McClarkin, chief executive of the British Beer and Pub Association (BBPA), said the required distance should be reduced to at least one metre, as in several European countries and advised by the World Health Organisation (WHO).

Kate Nicholls, chief executive of UK Hospitality, added that the reduction would also make businesses more viable, saying: “If you have two metres social distancing that’s the difference between opening at 30% of normal revenues, or 60% with one metre social distancing.”