People who test positive for coronavirus or display symptoms must now self-isolate for 10 days as Health Secretary Matt Hancock warned of a 'second wave starting to roll across Europe'.

The UK's chief medical officers said on Thursday the period must increase from the current rule of seven days because of the risk individuals may still be able to spread Covid-19.

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In a joint statement, they said the change for those who experience the key symptoms of a new continuous cough, high temperature or loss of taste or smell is needed because of the 'low but real possibility of infectiousness' up to 10 days.

Mr Hancock earlier warned that a new spike in Covid-19 cases is 'clearly' beginning to emerge in Europe as he said 'we've got to do everything' to prevent it reaching the UK.

"I am worried about a second wave. I think you can see a second wave starting to roll across Europe and we've got to do everything we can to prevent it from reaching these shores and to tackle it," Mr Hancock told Sky News.

He said 10-day isolation measure was "part of that, but so too are the measures we're taking, for instance, to ensure that we don't directly bring cases back to this country where there's a big spike in cases.

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"So, absolutely, on a second wave it is something I worry about and I worry about it because we can see it happening."

Scientists at Cambridge University have said it is 'very likely' that most regions in England are close to the point at which the virus begins to spread exponentially.

The chief medical officers for England, Wales, Scotland and Northern Ireland said that it is 'now the correct balance of risk' to extend the isolation period for those who test positive or have symptoms to 10 days.

They said: "Evidence, although still limited, has strengthened and shows that people with Covid-19 who are mildly ill and are recovering have a low but real possibility of infectiousness between seven and nine days after illness onset."

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Mr Hancock also warned travellers that new countries could be added to the quarantine list in the coming days after passengers arriving in the UK from Spain were ordered to isolate for two weeks as cases there increased.

He said ministers are looking at ways to reduce the 14-day period, possibly by the use of multiple tests, amid pressure from the tourism industry.

But he said ministers are constantly considering whether to add countries to the quarantine list and when pressed if new nations could be added in the next few days, he replied: "Yes."