The UK has extended the period of coronavirus self-isolation from seven to 10 days, as fears grew over a surge in cases.
Its chief medical officers said scientific evidence now showed that people with the virus have a "real possibility of infectiousness between seven and nine days".
"It is now the correct balance of risk to extend the self-isolation period from seven to 10 days," they said, as ministers hinted they would take new precautions to try and contain the pandemic.
At the weekend, the UK introduced a 14-day quarantine period for anyone returning from Spain, the UK's most popular tourist destination.
British Prime Minister Boris Johnson has warned of a "second wave" of cases in Europe and health secretary Matt Hancock said the government would announce similar measures to those imposed on Spain elsewhere, if necessary.
The latest official figures showed 753 people becoming infected with the virus yesterday.
The UK recorded a daily high of more than 8,700 cases in early April.
However, opposition MPs accused the government of panicking over the latest infection rates across mainland Europe.
The UK has been the worst affected country by the virus in Europe, officially recording almost 46,000 deaths.
The statement from the senior medical officials came as the Office for National Statistics announced that England had "the longest continuous period of excess mortality of any country" in the first half of this year.
Meanwhile, people from different households in Greater Manchester, parts of East Lancashire and West Yorkshire are banned from meeting each other indoors from midnight tonight as part of "immediate action" to keep people safe, British Health Secretary Matt Hancock said.
He tweeted: "We're constantly looking at the latest data on the spread of coronavirus, and unfortunately we've seen an increasing rate of transmission in parts of Northern England.
"The spread is largely due to households meeting and not abiding to social distancing. So from midnight tonight, people from different households will not be allowed to meet each other indoors in these areas.
"We take this action with a heavy heart, but we can see increasing rates of covid across Europe and are determined to do whatever is neccessary to keep people safe."
England records most virus excess deaths in Europe
Meanwhile, England recorded the most excess deaths in Europe in the first half of 2020, while Spain saw the highest peak in fatalities as the coronavirus ravaged the continent, data showed.
Britain's Office for National Statistics (ONS) found England had higher above-average death numbers for longer than all European countries from the end of February to mid-June.
Spain registered the second-highest toll in excess deaths - defined as the number of fatalities registered in excess of the five-year average - while Scotland saw the third worst figures, the ONS said.
Meanwhile Spain also saw the highest national peak in excess mortality in late March, followed by Italy, with some local areas recording rates 600-850 percent above the average.
"While none of the four UK nations had a peak mortality level as high as Spain... excess mortality was geographically widespread throughout the UK during the pandemic," said Edward Morgan, of the ONS.
"Combined with the relatively slow downward 'tail' of the pandemic in the UK, this meant that by the end of May, England had seen the highest overall relative excess mortality out of all the European countries compared."
The ONS analysis, its first international comparison of deaths related to Covid-19, relied on data published by the European Union's statistics body Eurostat, which also gathers input from several non-EU countries.
The Spanish capital Madrid has been the worst-hit major European city for excess deaths, with a peak in the week ending 27 March.
However, by the last week in May, England had recorded so many weeks of above-average deaths that it led the European comparisons.
The London district of Brent saw the highest peak of excess deaths of any area in the nation, while Birmingham registered the highest peak for an entire English city, in mid-April.
The UK government's daily count of deaths by people who had tested positive for Covid-19, also shows the country has suffered the deadliest outbreak in Europe.
That toll, a less comprehensive measure than excess mortality, currently stands at 45,961 deaths.
However, the ONS has already reported that Britain recorded 65,000 more deaths than usual during the first few months of the pandemic to the end of June.