Australian authorities have said that an international traveller who was most likely infected with the Omicron variant has spent time in the community as officials rush to track the person's close contacts and locations visited, Reuters reports.

New South Wales health officials said initial testing "strongly indicates" the traveller who arrived in Sydney last week before the latest border restrictions has been infected with the Omicron variant of the coronavirus.

The fully vaccinated person visited a busy shopping centre in Sydney while likely infectious, officials say. All passengers in the person's flight have been asked to self-isolate for 14 days regardless of their vaccination status.