Australian authorities have confirmed that a person with Covid-19 had the new Omicron variant after disclosing that the person had been active in the community, but urged calm as they weighed up the severity of the strain.
The fully vaccinated person visited a busy shopping centre in Sydney while likely infectious, officials said.
All passengers on the person's flight were asked to self-isolate for 14 days regardless of their vaccination status.
The additional case brings Australia's total number of infections with the new variant to six. But it is the first case where the person appeared to be active in the community.
All other cases have been in quarantine and are asymptomatic or display very mild symptoms.
Authorities also said urgent genomic tests have begun to determine whether two other positive cases on the same flight were infected with the Omicron variant.
The report about the new community case came as Australia's emergency cabinet - a group of federal and state leaders - met to review measures aimed at limiting the spread of the variant.
The country already delayed the reopening of its international borders by two weeks, less than 36 hours before international students and skilled migrants were to be allowed to re-enter the country.
New South Wales, home to a third of Australia's 25 million population, increased fines for overseas arrivals who did not comply with a mandatory 72-hour self-isolation, to A$5,000 from A$1,000 for individuals and to A$10,000 from A$5,000 for corporations.
The state, which recently emerged from four months of lockdown, has been unwinding its system of mandatory hotel quarantine but has said arrivals from several southern African countries must still spend 14 days in quarantine.
But the federal government urged state leaders to go ahead with plans to relax domestic border restrictions, which have been in place sporadically since the start of the pandemic, by Christmas.
"We need to make calm decisions. Don't get spooked by this," Prime Minister Scott Morrison said at a news conference in Canberra.
Health Minister Greg Hunt said the overwhelming view of medical experts was that "while it's an emerging variant, it's a manageable variant".
Omicron, dubbed a "variant of concern" by the World Health Organization, is potentially more contagious than previous variants although there are signs it may be milder than initially feared.
Tough border restrictions and snap lockdowns have helped Australia keep its Covid-19 numbers relatively low, with around 210,000 cases and 2,006 deaths.