Nations across Europe moved to reimpose tougher measures to stem a new wave of COVID-19 infections spurred by the highly transmissible Omicron variant, with the Netherlands leading the way by imposing a nationwide lockdown.

Starting Sunday, all non-essential stores, bars and restaurants in the Netherlands will be closed until Jan. 14, caretaker Prime Minister Mark Rutte said at a hastily arranged news conference Saturday night. Schools and universities will shut until Jan. 9, he said.

The lockdown terms also rein in private holiday celebrations. Residents will only be permitted two visitors except for Christmas and New Year's, when four will be allowed, according to Rutte.

He said the move was "unavoidable because of the fifth wave caused by the Omicron variant that is bearing down on us."

It wasn't just the Dutch seeking to slow the spread of Omicron. Alarmed ministers in France, Cyprus and Austria tightened travel restrictions. Paris cancelled its New Year's Eve fireworks. Denmark closed theaters, concert halls, amusement parks and museums. Ireland imposed an 8 p.m. curfew on pubs and bars and limited attendance at indoor and outdoor events.

London Mayor Sadiq Khan underscored the official concern about the climbing cases and their potential to overwhelm the health care system by declaring a major incident Saturday, a move that allows local councils in Britain's capital to coordinate work more closely with emergency services.

Irish Prime Minister Micheál Martin captured the sense of the continent in an address to the nation, saying the new restrictions were needed to protect lives and livelihoods from the resurgent virus.

"None of this is easy," Martin said Friday night.

"We are all exhausted with COVID and the restrictions it requires. The twists and turns, the disappointments and the frustrations take a heavy toll on everyone. But it is the reality that we are dealing with."

The World Health Organization reported Saturday that the Omicron variant of the coronavirus has been detected in 89 countries, and COVID-19 cases involving the variant are doubling every 1.5 to three days in places with community transmission and not just infections acquired abroad.

Major questions about Omicron remain unanswered, including how effective existing COVID-19 vaccines are against it and whether the variant produces severe illness in many infected individuals, WHO noted.

Yet Omicron's "substantial growth advantage" over the delta variant means it is likely to soon overtake delta as the dominant form of the virus in countries where the new variant is spreading locally, the UN health agency said.

In the Netherlands, anticipation a government meeting Saturday would result in tougher restrictions caused shoppers to swarm commercial areas of Dutch cities, fearing it would be their last chance to buy Christmas gifts.

Rotterdam municipality tweeted that it was "too busy in the centre" of the port city and told people: "Don't come to the city." Amsterdam also warned that the city's main shopping street was busy and urged people to stick to coronavirus rules.

In the U.K., where confirmed daily cases soared to record numbers this week, the government has reimposed a requirement for masks to be worn indoors and ordered people to show proof of vaccination or a recent negative coronavirus test when going to nightclubs and large events.

But the moves are causing anger.

Critics of British Prime Minister Boris Johnson's latest coronavirus restrictions flooded Oxford Street, a popular London shopping area, on Saturday. The maskless protesters blew whistles, yelled "Freedom!" and urged passersby to remove their face coverings.

Hundreds of people blocked traffic as they marched with signs bearing slogans such as "Vaccine passports kill our freedoms" and "Don't comply." Other signs had the faces of Johnson or U.K. Health Secretary Sajid Javid and read, "Give them the boot."

PHOTOS | Protesters march in London as Omicron takes hold:

Photogallery | COVID-19 protesters march in London as Omicron takes hold

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In France, the government announced that it will start giving the vaccine to children in the five to 11 age group beginning Wednesday. Prime Minister Jean Castex said Friday that with the Omicron variant spreading like "lightning," the government proposed requiring proof of vaccination for those entering restaurants, cafes and other public establishments. The pending measure requires parliamentary approval.

Demonstrations were planned in Paris to oppose the vaccine pass proposal and ongoing government restrictions.

Thousands of opponents of vaccine requirements and mask mandates protested Saturday in Hamburg, Berlin, Dusseldorf and other German cities. In Austria, local media reported the crowds swelled to tens of thousands.