The World Health Organization expressed concern Friday over a coronavirus resurgence in Europe as Britain joined France, Germany and Austria in announcing tighter mask rules and greater testing.

Europe accounts for a fifth of the world's more than 15 million infections and remains the hardest-hit region in terms of deaths, with 207,118 out of more than 630,000 globally since the virus emerged in China late last year.

The WHO's European chapter pointed to rising cases on the continent over the past two weeks, saying tighter measures may be needed to curb the spread.

Europe like other regions is struggling to balance restrictions to halt COVID-19 against the need to revive economies as people there emerge from some of the world's toughest lockdowns.

A three-year-old girl died in Belgium, becoming the country's youngest known coronavirus victim, in a further wake-up call for a continent that has recently lifted shutdowns.

"The recent resurgence in COVID-19 cases in some countries following the easing of physical distancing measures is certainly cause for concern," a WHO-Europe spokeswoman told AFP.

"If the situation demands, reintroduction of stricter, targeted measures with the full engagement of communities may be needed."

In Spain, health authorities are facing worrying outbreaks in Aragon and Catalonia, where officials have reintroduced local restrictions and urged residents in Barcelona and its suburbs to leave home only for essential trips for two weeks.

"We have to monitor what's going on, see where we need to take action and act early," said health ministry official Maria Jose Sierra.

"If the important outbreaks are controlled quickly and if we manage to ensure that there are no (other) outbreaks of such magnitude, we will have a much more contained situation."

- On-the-spot tests -
French President Emmanuel Macron on Friday met his top ministers to discuss contagion measures, and his prime minister Jean Castex later announced on-the-spot tests would be required for travellers visiting from 16 high-risk countries including the United States.

France has yet to resume general travel to and from these countries so the tests will be for returning French citizens and residents.

Masks are now mandatory on public transport, in shops and enclosed spaces across France and there are fears that the summer holidays could see a spike in cases with people flocking to beaches and tourist spots. 

Britain on Friday made it compulsory to wear a face-covering in shopping centres, banks, takeaway outlets, sandwich shops and supermarkets, following the lead of Scotland.

Exceptions have been made, including for children under 11 or people with respiratory problems, but others who refuse to cover their nose and mouth risk a fine of up to £100.

Germany will offer free coronavirus tests to all returning travellers in new measures agreed Friday.

And Austria made face masks mandatory again in supermarkets, food stores, post offices, bank branches and health care facilities along with public transport and pharmacies.

"It was a mistake to lift mandatory mask use so soon," said one shopper, Andreas Poschenreither.

- Trump convention scrapped -
The United States, the country hardest-hit by the virus, has now recorded 145,324 deaths and 4.1 million infections. For the second day running on Friday it reported more than 70,000 new cases and more than 1,000 fatalities in a 24-hour period, according to a tally maintained by Johns Hopkins University.

The nation is in the grip of a surge particularly in southern and western states.

US President Donald Trump has scrapped next month's Republican convention in Florida at which he was due to be confirmed as the Republican candidate for November's election, saying "the timing for this event is not right".

Bolivia meanwhile postponed its general election for a second time because of the pandemic, putting it off until October 18, while South Africa said it was closing public schools for a month from July 27.

There was also bad news in China and India -- the world's two most populous nations -- as new clusters emerged.

Chinese authorities said Friday they would introduce a wave of testing in the port city of Dalian, home to about six million people.

The Dalian health commission said the city had to "quickly enter wartime mode" to stop any spread. It announced strict new measures, including on-the-spot nucleic acid tests.

Kindergartens and nurseries have been closed, and some communities have been placed under lockdown, according to state-run newspaper Global Times.

India's death toll overtook France's on Friday at 30,601. Officials said there were nearly 50,000 new cases of the virus overnight.

Prime Minister Narendra Modi's government imposed one of the world's strictest lockdowns in late March but it has been steadily eased to lessen the devastating economic impact.

State governments have now brought in fresh restrictions as cases soar, including in the IT hub Bangalore.

UN projections have warned the virus could kill 1.67 million people in 30 low-income countries.

Virus restrictions have been bolstered in several other countries this week, including Australia and Belgium, as well as in Hong Kong and the Japanese capital Tokyo.

US marks second day with 70,000-plus virus cases

For the second day running, the United States on Friday recorded more than 70,000 new coronavirus cases and more than 1,000 deaths in a 24-hour period, according to a tally maintained by Johns Hopkins University.

The world's hardest-hit country registered 73,795 new cases of COVID-19 with 1,157 additional deaths, the Baltimore-based university's real-time tracker indicated at 8:30 pm (0030 GMT Saturday).

That brings the country to a total of 4.1 million infections, which have resulted in 145,324 fatalities.

A total of 1.26 million people have recovered from the disease.

After a drop in the rate of infections in late spring, the US has seen a coronavirus surge, particularly in southern and western states like  California, Texas, Alabama and Florida. 

For the past 11 days, the number of new cases being reported each day has topped 60,000.

Scientists agree that an increase in death rates follows the spike in infections by three to four weeks.

After regularly surpassing 500 deaths a day around the end of June, the daily toll for the past three days has exceeded 1,000.

South Korea sees surge in new cases

South Korea reported a surge in new coronavirus infections on Saturday, recording its highest figure in nearly four months with dozens of imported cases.

The country added 113 new cases, including 86 among people who arrived from overseas, bringing the total to 14,092, according to the Korea Centers for Disease Control and Prevention.

It was the second-highest figure since March 31, when the country reported 125 new cases. It was also the first time it has seen more than 100 cases since April 1.

All overseas arrivals are required to undergo a two-week quarantine.

South Korea endured one of the worst early outbreaks outside China but brought it broadly under control with an extensive "trace, test and treat" programme while never imposing a compulsory lockdown that was put in place in much of Europe and around the world.

The country has been seen as a model on how to combat the pandemic with the public largely following safety health measures such as wearing face masks.

Vietnam detects first case in 100 days

Vietnam has detected its first locally-transmitted case of coronavirus in nearly 100 days, authorities said Saturday, in a country whose swift and full lockdown won praise for controlling the spread of the disease. 

"Patient 416" is a 57-year-old retired Vietnamese man in the southern city of Danang, and the first community transmission since April 16.

Local health officials have tested 105 people who had been in close contact with him, the Ministry of Health said on its website.

The man had taken his mother to a hospital in the days before after showing symptoms of the sickness, authorities said, but gave no confirmation of how he was infected in a country where the virus appeared to have been stubbed out for several months.

"The patient is currently on ventilator support due to respiratory failure," it said, adding his family believe his contacts with others were limited.

"He didn’t go out of the city and only stayed at home to look after his grandchild and interact with neighbours, he didn’t make contact with strangers," it said.

Danang has been packed with local tourists returning to its beaches and restaurants since Vietnam lifted its lockdown.

Despite sharing a long, ungovernable border with China, Vietnam has recorded just 416 virus cases -- including the latest from Danang -- with no deaths.