(Reuters) - Australia, despite restrictions on international visitors, became the latest country on Friday to report community transmission of Omicron, a day after the coronavirus variant was found locally in five U.S. states.

U.S. President Joe Biden warned on Thursday that infections will rise during the northern-hemisphere winter and the European Union's public health agency said Omicron could account for more than half of all infections in Europe within months.

Australia's chief medical officer on Friday said Omicron was likely to become the dominant variant globally within months, but at this stage there was no evidence it was any more dangerous than Delta which swept the world earlier this year.

"I suspect within the [next few] months, Omicron will be the new virus in the world," Paul Kelly, the top medical advisor to the Australian government, told reporters.

His comments came after Australia reported its first case of community transmission even though it has closed its borders to high-risk southern Africa, one of a growing number of countries that have imposed travel restrictions to keep the variant out.

Global travel curbs accelerated on Thursday, with Hong Kong, the Netherlands, Norway and Russia, among others, announcing fresh measures to prevent the variant crossing their borders.

Such restrictions are wreaking havoc with the travel industry, pounding financial markets and undermining major economies just as they were beginning to recover from the lockdowns triggered by Delta.

Shares in Tokyo and South Korea fell on Friday after overnight losses on Wall Street, but traders will need to wait at least another week or so for answers from global health authorities on the variant's virulence or vaccine resistance.

Europe's biggest economy, Germany, said it would bar the unvaccinated from all but essential businesses, and legislation to make vaccination mandatory would be drafted for early next year.

Several countries including Britain and the United States were bringing forward plans to offer booster shots, but, like travel bans, this is controversial. Australian authorities said on Friday there was "no evidence" such moves would be effective.