SYDNEY (Reuters) - Australia's political leaders were set to hold an emergency meeting on Wednesday as cases of the Omicron coronavirus variant broke infection records and forced countries around to world to double down on vaccinations, just days before Christmas.

Authorities globally have imposed new restrictions and stepped up inoculation efforts as Omicron emerges as the dominant strain of the virus, upending imminent reopening plans that many governments hoped would herald the start of a post-pandemic era in 2022.

Singapore will freeze all new ticket sales for flights and buses under its programme for quarantine-free travel into the city-state from Dec. 23 to Jan. 20, the government said on Wednesday, citing risk from the fast-spreading Omicron.

President Joe Biden on Tuesday promised half a billion free rapid COVID-19 tests and warned the quarter of American adults who are unvaccinated that their choices could spell the "difference between life and death."

In response to the surge in cases, Asia-Pacific countries are also looking to shorten the time between second vaccination shots and boosters. However, wary of public lockdown fatigue, there is reluctance to return to the strict curbs imposed during the spread of the Delta variant earlier this year.

Australian Prime Minister Scott Morrison on Wednesday urged leaders of the country's states to reopen hundreds of vaccination hubs to accelerate the rollout of booster shots after they were shut down as demand slowed when double-dose rates in people above 16 years topped 80 percent.

"That's a very important part of today's discussion," Morrison said ahead of a snap meeting of national Cabinet on Wednesday, which includes of federal and state leaders.

He said decisions about bringing forward the vaccination scheduled would depend on expert advice.

Australia on Wednesday reported more than 5,000 daily infections for the first time during the pandemic, eclipsing the previous high of around 4,600 a day earlier, with the bulk of cases in its most populous states of New South Wales and Victoria.

Despite the Omicron surge, Morrison on Tuesday ruled out lockdowns and insisted that limiting the spread of the virus comes down to personal responsibility.

There was also resistance to new lockdowns in South Korea, where authorities announced restrictions on gatherings and operating times for restaurants, cafes and bars.

While polls still show wide support for South Korea's fresh curbs, some of its strictest yet, many small businesses have complained that restrictions leave them overstaffed and overstocked, having prepared for a holiday season under looser rules.

Small business and restaurant associations issued statements protesting the decision and calling for compensation, with one of the groups vowing to stage a demonstration on Wednesday.

New Urgency

Hans Kluge, the World Health Organization's European head, on Tuesday warned of a "storm" that Omicron would bring, "pushing already stretched health systems further to the brink."

Germany, Scotland, Ireland, the Netherlands and South Korea are among countries that have reimposed partial or full lockdowns or other social distancing measures in recent days.

Portugal ordered nightclubs and bars to close and told people to work from home for at least two weeks from Saturday.

British Prime Minister Boris Johnson said he would not introduce new COVID-19 curbs in England before Christmas, but the situation remained extremely difficult and the government might need to act afterwards.

Governments have stepped up vaccination and treatment efforts with the U.S. Food and Drug Administration set to authorise COVID-19 treatment pills from Pfizer Inc and Merck , Bloomberg News reported.

Israel will offer a fourth dose of the COVID-19 vaccine to people older than 60.

For now, financial markets have taken Omicron's spread in their stride, having reclaimed some of the heavy losses made after virus headlines earlier this week.

Policymakers are, however, scrambling to address the economic hit that might come from new outbreaks with Britain announcing 1 billion pounds ($1.3 billion) of extra support for businesses hit hardest by Omicron.

With much still not known about the severity of Omicron infections, businesses are also worried about a swathe of cancellations affecting big-ticket events in the new year.

North America's National Hockey League will not send its players to compete in the men's ice hockey tournament at the Beijing Winter Olympics due to COVID-19 concerns, ESPN reported on Tuesday.

That would not only affect league players in the U.S. and Canadian ice hockey teams, but also those in the Olympic squads of Sweden, Finland and Germany

(Reporting by Renju Jose in Sydney, Josh Smith in Seoul; Writing by Sam Holmes; Editing by Michael Perry)