PARIS: France said Thursday that it would ban non-essential travel to and from Britain in a bid to keep the Omicron Covid-19 variant in check, as European leaders urged coordinated action and more booster shots to counter the more highly contagious threat.

Countries worldwide have begun advising against foreign travel while ramping up domestic restrictions to battle Omicron, even though scientists remain uncertain how dangerous it is.

Britain has seen case levels explode in recent weeks to record levels amid fears the variant could overwhelm hospitals during the dinners and parties for the year-end holidays.

Starting at midnight Saturday (2300 GMT Friday), the French government said, travellers will need "an essential reason to travel to, or come from, the UK, both for the unvaccinated and vaccinated... People cannot travel for touristic or professional reasons."

It added that French citizens and EU nationals could still return to France from the UK, but they will now need a negative Covid test less than 24 hours old, and a blanket quarantine will be enforced upon their return.

The Spanish government said meanwhile that boosters would soon be available for everyone aged 40 and older, down from 65 and older currently.

EU drug regulators on Thursday also approved Pfizer's Covid pill for emergency use by member states struggling with the new coronavirus wave.

'Tightening the net'

In France, the "drastic" new limits on travel to Britain aim to give the country time to give 20 million booster jabs by Christmas -- and the country may soon open up vaccinations to children aged 5 to 11.

"People (coming back) will have to register on an app and will have to self-isolate in a place of their choosing for seven days -- controlled by the security forces -- but this can be shortened to 48 hours if a negative test is carried out in France," government spokesman Gabriel Attal said.

Britain on Thursday recorded a record 88,376 laboratory-confirmed Covid cases, with scientists predicting even higher rates as Omicron is believed to spread much faster than the currently dominant Delta variant.

"It's down to individual countries to decide their approach," a spokesman for British Prime Minister Boris Johnson said in response to the French restrictions.

"We've maintained that travel abroad will be different this year and that countries may impose border measures at short notice," he added.

At the Eurostar terminal at St Pancras station in London, many passengers were scrambling to change tickets to arrive in Paris before Saturday and pass the holidays with family.

"I have friends who are panicking," said Marie Geoffroy, a 43-year-old who lives in London who was about to board.

"These last-minute changes are stressful, it feels like you've been taken hostage," she said.

'Fear the worst'

The French move comes after Canada urged its citizens to avoid foreign travel over the Christmas holidays, with Health Minister Jean-Yves Duclos saying the Omicron variant "makes us fear the worst."

South Korea said it would reimpose coronavirus curfews on restaurants, cinemas and other businesses and limit the size of gatherings again in the face of record infection levels.

New York's Metropolitan Opera, meanwhile, announced that it will require Covid booster shots from all its musicians and other employees -- some 3,000 people -- as well as anyone attending a performance.

The Omicron risk also elbowed its way into an EU summit meeting in Brussels on Thursday, with predictions the variant could become dominant in the bloc as soon as next month.

But leaders are struggling to forge a united approach to stop the spread, after several countries imposed emergency measures in recent days.

Omicron is "of significant concern obviously, in terms of the capacity of that variant to spread rapidly and create pressure on our societies and our health systems," Irish Prime Minister Micheal Martin told journalists in Brussels.

"So today we'll be looking for greater coordination on a number of fronts," he said.