Australian authorities reported another probable case of the Omicron variant in Sydney on Wednesday, as they braced for additional illnesses following the visit of at least two overseas tourists to multiple areas throughout the city while possibly contagious.

Officials in the state of New South Wales (NSW), which includes Sydney, said preliminary testing "clearly indicates" that a guy in his 40s who arrived from southern Africa on Nov. 25 was infected with the Omicron strain and spent time in the community.

To comply with Commonwealth requirements, all travelers from South Africa, Lesotho, Botswana, Zimbabwe, Mozambique, Namibia, Eswatini, and Malawi must spend 14 days in hotel quarantine.

All other international tourists must now have a PCR test and isolate for 72 hours at their home, after which they may depart if the result is negative.

"We feel it is likely that a verified Omicron case will be confirmed later this afternoon," NSW Health Minister Brad Hazzard told reporters, but he ruled out lockdowns to contain the newly found variant.

Sydney, Australia's largest city, emerged from a nearly four-month lockdown in early October to contain a Delta outbreak and has been gradually reducing restrictions in response to increased vaccination rates.

Omicron has pushed Australia to postpone by two weeks its plans to reopen its borders to skilled migrants and international students on Wednesday. Citizens returning from southern African countries are required to undergo a mandatory two-week quarantine.

Vaccinated Australians arriving in Sydney and Melbourne from other countries must now undergo a 72-hour quarantine. Other states have not yet opened their borders to the rest of the world.

"It's quite perplexing, it was extremely emotional... I prayed a lot. I figured I'd land here and see what happens "Lorelle Molde, who arrived in Australia from the United States, told Reuters at Sydney's international airport.

When confirmed, the latest probable case would increase Australia's confirmed infection count to seven, with six found in New South Wales.

The World Health Organization (WHO) has urged governments to be calm and take "rational" actions in response to the Omicron coronavirus outbreak.

"We urge all member states to implement logical, proportional risk-reduction measures," WHO Director-General Tedros Adhanom Ghebreyesus said during a Tuesday briefing.

Although the origins of the new variant are unknown, concerned nations have rushed to tighten travel restrictions, particularly on travelers from Southern Africa.

Authorities confirmed the country's first community case of the new strain on Tuesday, but the national cabinet opted against tightening restrictions in the absence of additional information on the disease's severity and transmissibility.

COVID-19 has been linked to around 212,000 cases and 2,012 deaths in Australia.