The World Health Organisation has cast doubt on the UK’s approach to developing "herd immunity" against Covid-19, saying the current situation around the outbreak in Britain requires "action".

Spokeswoman Margaret Harris said scientists do not know enough about the virus to say whether "theories" around people becoming immune to it are correct.

On Friday, the UK’s chief scientific adviser Sir Patrick Vallance hit back at criticism over the Government's handling of the virus and said the approach would hopefully create a “herd immunity” to the disease.

Former Health Secretary Jeremy Hunt was among those to ask why the Government had not cancelled large gatherings as part of the measures, but Sir Patrick said some of the social distancing measures put in place - including self-isolating for seven days if symptoms develop - were "actually quite extreme".

Questioning the approach, WHO spokeswoman Dr Harris told BBC Radio 4’s Today: “We don’t know enough about the science of this virus, it hasn’t been in our population for long enough for us to know what it does in immunological terms.

“Every virus functions differently in your body and stimulates a different immunological profile.

“We can talk theories, but at the moment we are really facing a situation where we have got to look at action.”

Her comments come as plans get under way to ban mass gatherings from next week as the Government looks to implement more extreme measures in the fight against Covid-19.

Boris Johnson had faced criticism for not taking such actions, despite similar steps being taken by other European countries as the pandemic worsens. Emergency legislation bringing in beefed-up powers will be published next week and there could also be a move towards more people working from home, a Whitehall source said.

The Times reported the laws could also give police and immigration officers to detain people if they are suspected of being infected and the ability to direct schools to stay open. The newspaper said the laws could remain in place for two years.

Scores of major sporting and cultural events have already been suspended, despite the Government resisting calls to ban mass events in its latest guidance earlier this week. Scotland had already announced a ban on gatherings of more than 500 people.​

Care Minister Helen Whately told the BBC: “We are following the evidence. As the chief medical officer said, and I have been advised, the evidence tells us that stopping mass gatherings doesn’t have a huge impact on the spread of the virus.

“But, for example, decisions have been taken in some countries because of the impact on public services and because, when you have a mass gatherings, that draws on the police and the ambulance service you need to support it.”