Omicron cases are doubling every 1.5 to three days and the variant has been detected in 89 countries as it sweeps the world and impacts Christmas and New Year festivities.

The World Health Organisation (WHO) said the highly transmissible virus was spreading rapidly even in countries with high levels of vaccination.

It comes as a winter COVID surge in Europe has led to the cancellation of big outdoor gatherings and events for New Year in France and Rome, while the Netherlands announced an “unavoidable” Christmas lockdown.

Non-essential shops, bars, gyms, hairdressers and other public venues will be closed until at least mid-January while guests to the home will be limited to two per household and four during the holiday period.

“I stand here tonight in a sombre mood. And a lot of people watching will feel that way too,” Dutch Prime Minister Mark Rutte told a news conference.

“To sum it up in one sentence, the Netherlands will go back into lockdown from tomorrow.”

The UK recorded 10,000 Omicron cases (of more than 90,000 coronavirus infections) as London’s mayor declared a “major incident” because of COVID’s impact on the city, including staff absences in essential services.

Meanwhile in Australia, coronavirus cases smashed another national record on Saturday after more than 4,000 cases were reported only two days after breaking through 3,000.

There were 4110 infections nationwide, the bulk of which were in NSW (2482 new infections) — the most in a single day for any Australian state or territory during the pandemic.

Saturday’s record case numbers in NSW eclipsed the previous mark of 2297 set by Victoria on October 14 and health experts said it was likely most of the latest cases were Omicron.

Victoria added 1504 cases along with seven virus-related deaths.

South Australia posted a second consecutive state record with 73 cases, Queensland recorded 31 and the ACT 18.

Tasmania confirmed a fourth case after reopening its border to fully vaccinated travellers on Wednesday.

Even so, Prime Minister Scott Morrison warned living with the virus under the national plan was not about case numbers.

“We’re past the time when we just talk about case numbers. It is a leading indicator on some issues, but the real issue is how many people are experiencing serious illness,” he told reporters in Hobart on Saturday.

“What matters is hospitalisations, ICU, people on ventilators and severe illness.”

There are 384 patients in hospital in Victoria, and 206 in NSW.

In NSW, a handful of positive cases at a Byron Bay caravan park meant dozens of guests — including schoolies — have had to isolate inside their caravans and cabins.

In Victoria, an outbreak at Camp Rumbug in South Gippsland that began last week has grown to about 50 cases across two Melbourne schools, with hundreds of people forced into isolation.

‘Major incident’ in London

A major incident has been declared in London amid “huge concern” at the spread of the Omicron coronavirus variant across the capital.

London Mayor Sadiq Khan also said he was “incredibly worried” about staff absences in vital public services including the NHS, fire service and police due to rapidly rising cases.

The declaration of a major incident will allow authorities to work together and support each other to reduce service disruption and allow more time to give out booster jabs, the mayor’s office said.

Mr Khan said: “The surge in cases of the Omicron variant across our capital is hugely concerning, so we are once again declaring a major incident because of the threat of COVID-19 to our city.

“The Omicron variant has quickly become dominant, with cases increasing rapidly and the number of patients in our hospitals with COVID-19 on the rise again.

“We are already feeling the impact across the capital and while we are still learning about this variant, it’s right that London’s key agencies work closely together to minimise the impact on our city, including helping to protect the vital vaccination programme.”

-with AAP