Health Secretary Matt Hancock has hinted that the length of time people with coronavirus symptoms must self-isolate for will be increased to 10 days in England.

Asked about the move, he told Sky News: "This is a decision that's clinically led. The chief medical officer will be setting out details later today.

"I can't steal his thunder but what I will say is we will always do what is necessary to protect people and we're guided by the clinical judgment, by the science in this."

Health Secretary Matt Hancock warned that a "second wave" of coronavirus is "starting to roll across Europe".

He told Sky News: "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.

"The measures that the chief medical officer will set out later are 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.

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

Health Secretary Matt Hancock also said ministers were investigating ways to reduce the 14-day quarantine period for new arrivals to the UK from at-risk countries.

Asked about reports, he told Sky News: "We're always looking at how we can have the least-possible burden of the measures that we have to put into place so that is something on which we're doing some work but we'll only come forward with a proposal when we're confident that it is safe to do so.

"So again this is very much guided by the clinical science and the CMO (chief medical officer) will be speaking on it later today, but the broader point is that there's a serious concern about a second wave that's clearly now moving across Europe and we need to take action.

"If that means increasing the number of days that people who test positive have to self-isolate then so be it because these measures are necessary to keep people safe."

Health Secretary Matt Hancock told BBC Breakfast there would be no changes in the next few days to quarantine rules for people returning from overseas, including Spain.

He said work was ongoing on whether testing people during the 14-day quarantine period would mean it was safe to release them earlier.

"This is a really important, essentially scientific clinical question, so that's something that we're working on," he said.

"But we are not imminently making an announcement on it because that work is not concluded, and until it is absolutely safe to make that sort of change, then we won't do so, but it is something that we're working on."

Health Secretary Matt Hancock declined to confirm that isolation rules for people with symptoms would be extended to 10 days but said "the science on this has been developing and we want to take a precautionary approach to make sure that we can keep people in this country as safe as possible."

He told BBC Breakfast: "We can see, sadly, a second wave of coronavirus that is starting to roll across Europe, many European countries whose number of cases is going up again.

"And we want to do everything we possibly can to protect people here, and protect people from that wave reaching our shores."

He said decisions would be led by science, and a precautionary approach was needed "because of the concerns that we have of the potential of a second wave that is clearly coming in some countries across Europe."

He said some countries in Europe had had a very low rate of new cases but these were rising "quite sharply" in some areas.

Health Secretary Matt Hancock told BBC Breakfast that the "big scientific challenge" with testing people at the border was that you "can incubate this disease for many days without displaying any symptoms, and that wouldn't show up in a test".

He added: "So if people get off a plane coming from somewhere that has a high degree of disease and therefore they have to quarantine, if you get the test, and the test result comes back negative, you could still have the disease, you're just incubating it."

Mr Hancock said he was not against testing people at the border but more work was needed on the timing of Covid-19 tests to make them effective.

Health Secretary Matt Hancock said new countries could be added to the incoming travellers' quarantine list in the coming days.

He told BBC Radio 4's Today programme that ministers are looking at ways to reduce the 14-day period, possibly by the use of multiple tests.

"We don't know - that's one of the things we're looking at," he said.

He said ministers are constantly reviewing the list and, when pressed if new countries could be added in the next few days, he replied: "Yes."

The length of time people with coronavirus symptoms in England will have to self-isolate for is to be increased from seven to 10 days, England's deputy chief medical officer Professor Jonathan Van-Tam has confirmed.

He told reporters the change was being made due to the "low but real possibility of infectiousness" between seven and 10 days after the onset of the illness.

A joint statement from the UK's chief medical officers, Professor Chris Whitty, Dr Frank Atherton, Dr Gregor Smith and Dr Michael McBride said: "In symptomatic people Covid-19 is most infectious just before, and for the first few days after symptoms begin. It is very important people with symptoms self-isolate and get a test, which will allow contact tracing.

"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.

"We have considered how best to target interventions to reduce risk to the general population and consider that at this point in the epidemic, with widespread and rapid testing available and considering the relaxation of other measures, it is now the correct balance of risk to extend the self-isolation period from seven to 10 days for those in the community who have symptoms or a positive test result.

"This will help provide additional protection to others in the community. This is particularly important to protect those who have been shielding and in advance of the autumn and winter when we may see increased community transmission."