Australia on Monday night delayed the reopening of its international borders, less than 36 hours before international students and skilled migrants were due to be allowed to re-enter the country.
The country's health minister Greg Hunt said that while the delays were being implemented on the "presumption" that things will recommence from December 15, authorities will be guided by medical advice during that process.
Omicron, dubbed a "variant of concern" by the World Health Organization, is potentially more contagious than previous coronavirus variants although there are hopes the variant may be milder than initially feared, calming global financial markets.
The new variant was discovered just as Australia was gearing up to reopen its border to foreign visa holders on Wednesday in the latest step to restart international travel, having largely shut its borders in March 2020 to non-citizens.
A total of five cases of the newly identified variant first found in southern Africa have been detected in Australia so far - all vaccinated and in quarantine - after genomic tests confirmed three more infections on Monday.
Officials said all of the cases are asymptomatic or display very mild symptoms.