America's top infectious diseases expert has warned the United States is facing a "serious problem" from a resurgent coronavirus as the illness puts the brakes on reopening two of the country's largest states.

Texas and Florida closed bars and reimposed other curbs on Friday as the number of infections in the US hit a single-day record with increases in 16 states, mostly in the south and west.

The contagion also continued its march through Latin America, where Brazil recorded another 1,140 deaths and Argentina toughened a lockdown in the capital Buenos Aires.

In Europe, countries wrangled over plans to partially reopen the EU border, with officials fretting over the reliability of virus data from abroad, notably China, where COVID-19 first emerged late last year.

Much of the Western world is pressing ahead with lifting restrictions on daily life despite warnings from health officials that haste could cost more lives.

"We are facing a serious problem in certain areas," leading US immunologist Anthony Fauci said at the first briefing in two months by the White House's Coronavirus Task Force.

"The only way we're going to end it is by ending it together," he said of the outbreak.

The US is recording more than 30,000 cases daily. With nearly 125,000 lives lost, it has by far the highest confirmed death toll in the world.

Texas had been among the most aggressive states in easing curbs but its strategy has backfired with the nation's second most populous state seeing several daily records in the number of new infections. 

"It is clear that the rise in cases is largely driven by certain types of activities, including Texans congregating in bars," Governor Greg Abbott said.

- Border wrangling -

European diplomats said they planned to exclude the US from travel to the continent when the bloc's external frontier reopens on July 1.

EU envoys have argued on drawing up criteria and sources told AFP a meeting on Friday ended with a tentative list of about 18 countries free to travel.

With nations around the world at different stages on the outbreak curve, agreeing on "travel corridors" has proved tricky.

Britain said it will lift its two-week quarantine rule for visitors arriving from some "low-risk" countries after pressure from airlines.

Sweden lashed out at the World Health Organization for listing it among countries deemed at-risk. The country made headlines for its high death toll after opting not to introduce a strict lockdown.

"We have an increase in cases because we have begun testing much more in Sweden the past week," said Swedish state epidemiologist Anders Tegnell.

- Fundraising effort -

The WHO on Friday called for another $27.9 billion in donations to speed up the development and production of tests, vaccines and other treatments, part of its ACT accelerator plan to pool international resources.

About $3.4 billion has already been pledged, the global body said ahead of a major fundraising event in Brussels by the EU Commission on Saturday that will feature performances by celebrities including Shakira and Justin Bieber.

More than 490,000 people worldwide have now died from the virus and the number of cases is expected to reach 10 million in the next week, according to an AFP tally.

India clocked its 500,000th case on Saturday with a record daily leap of 18,500. The outbreak there is not expected to peak for several more weeks and experts say the number of cases could pass one million before the end of July.

Much of the global count has come from Latin America, where Brazil, the hardest-hit nation in the region, has logged almost 55,000 deaths and more than 1.2 million cases.

In neighbouring Argentina President Alberto Fernandez announced a tightening of lockdown measures in the capital as cases spike, adding people could only leave home "to fetch provisions for daily life".

With much of the world under lockdown for months, the virus has crippled economies and signs of the damage have been widespread.

In Southeast Asia the leaders of the 10-member ASEAN bloc said the pandemic would see the region's economy contract for the first time in 22 years.

"It has swept away the successes of recent years... threatening the lives of millions of people," Vietnam Prime Minister Nguyen Xuan Phuc said.

Panic-buying has also reared its ugly head again, with supermarkets in Australia imposing limits on purchases of toilet paper after people snapped up masses of stock, rattled by a surge in cases in Melbourne.

"Stop it, it's ridiculous," Prime Minister Scott Morrison told his compatriots.

Argentina cranks up lockdown

Argentina President Alberto Fernandez announced on Friday a toughening of lockdown measures in the capital Buenos Aires and its surrounding area as coronavirus cases are on the rise.

"We're going back to closing the Buenos Aires metropolitan area so that traffic dramatically decreases, to reduce infections and the need for (hospital) beds," said Fernandez.

From July 1 "we're going to ask everyone to return to isolation at home and to only leave to fetch provisions for daily life," he said.

The measure will last until July 17 with "only essential services and some industrial zones" remaining operational.

The decision comes with coronavirus cases increasing exponentially. Argentina now has more than 1,100 deaths and over 52,000 cases.

Fernandez said the greater Buenos Aires area, home to 14 million of Argentina's 44 million population, "is infecting the rest of the country," where 80 percent of activity has reopened.

Center-left leader Fernandez could not resist a dig at neighbor Brazil's far right President Jair Bolsonaro, saying that the prolonged quarantine had "saved lives."

"If Argentina had followed Brazil's rhythm, we'd have 10,000 dead," he said.

UK to ease rules for 'low risk' countries

Britain said Friday it will lift its two-week coronavirus quarantine rule for visitors arriving from some "low risk" countries, after pressure from airlines and the tourism sector.

The government said it will publish a list next week of the countries from where people will be allowed to enter Britain without needing to self-isolate for 14 days, as currently required.

The announcement will follow discussions with countries including France, Greece and Spain in "the coming days", with the changes set to take effect in the week beginning July 6.

"Our new risk-assessment system will enable us to carefully open a number of safe travel routes around the world," a UK government spokesman said.

The foreign office will also be updating its travel guidance, which currently advises against all non-essential travel outside Britain, to permit trips on travel corridors.

All passengers will be required by law to wear face coverings on planes and ferries, it added.

Britain introduced its quarantine regime for most travellers arriving into the country on June 8, vowing to review the measures every three weeks.

The rules also applied to any Britons who had left the country and were returning.

It has faced criticism -- and legal challenges -- from airlines hard-hit by the pandemic, as well as from others in the travel industry who have argued it will devastate the domestic tourism sector.

Ministers have insisted for weeks they were looking at creating so-called air bridges with countries with low rates of virus transmission. But they have yet to provide any clear details of the plan.

The government now says it has created a categorisation system for countries based on public health criteria, to determine if they are safe enough to be exempted. 

Countries have been classified as either green, amber and red, depending on their risk assessment.

The list has been informed by factors including the prevalence of the virus, the reliability of data, and "the trajectory of the disease in the country".

Countries in the green and amber categories are deemed low risk enough to receive exemptions.

The government maintains the new measures will be kept under constant review and quarantine rules could be reintroduced for individual countries if their situation changes.

"But we will not hesitate to put on the brakes if any risks re-emerge, and this system will enable us to take swift action to re-introduce self-isolation measures if new outbreaks occur overseas," the spokesman added.

Brazil appeals court order on wearing mask

Brazilian President Jair Bolsonaro appealed a court ruling Friday that requires him to wear a face mask in public during the coronavirus pandemic, calling it "unnecessary."

The attorney general's office, which represents the government in legal matters, said the ruling was redundant since face masks are already mandatory in Brasilia.

"This interference from the courts is unnecessary," a spokeswoman for the attorney general's office told AFP.

However, it is a regulation the far-right president has repeatedly flouted, as Judge Renato Borelli pointed out in his ruling Monday.

"The president has a constitutional obligation to follow the laws in force in the country," the judge wrote, ordering Bolsonaro to obey the regulation or face a 2,000-real ($365) fine.

The case was brought by a lawyer who said the president should be held to account for his "irresponsible behavior."

Since the ruling, Bolsonaro has worn a mask at all public appearances.

Masks have been mandatory in public in Brasilia since April to curb the spread of the virus.

Bolsonaro regularly breaks the social distancing measures in place in the capital, giving handshakes and hugs at rallies, hosting barbecues, hitting the shooting range and going out for hotdogs, generally without a mask.

The president, who has famously compared the virus to a "little flu," has railed against the measures state and local authorities are taking to fight it, arguing that business closures and stay-at-home measures are needlessly wrecking the economy.

Brazil has the second-highest COVID-19 death toll in the world, after the United States, at 55,000.

So far, Bolsonaro has never been fined for failing to wear a mask.

But his former education minister Abraham Weintraub was fined 2,000 reals last week for attending a pro-Bolsonaro rally in Brasilia without one.