SYDNEY (AFP, REUTERS) - Health officials in Australia said Sunday (Nov 28) they had detected the Covid-19 Omicron strain for the first time after testing two passengers from southern Africa who flew into Sydney.

The eastern state of New South Wales' health authority said it had conducted urgent genomic testing and confirmed the new strain was present in two passengers who landed in Sydney on Saturday.

Both passengers came from southern Africa and arrived in Australia on a Qatar Airways flight via Doha, NSW Health said in a statement.

They tested positive for Covid shortly after arriving, leading to an urgent analysis for possible infection by the heavily mutated Omicron strain.

"The two positive cases, who were asymptomatic, are in isolation in the special health accommodation. Both people are fully vaccinated," NSW Health said.

Another 12 passengers from southern Africa in the same flight did not test positive for Covid but have been placed in quarantine, it said.

About 260 passengers and crew on the plane have also been told to isolate, the health authority said.

Australia imposed new restrictions on Saturday on people who have been to nine southern African countries, as the highly infectious Omicron variant raises concerns about another wave of the pandemic.

Britain, Germany, Italy, the Czech Republic and Israel detected Omicron cases on Saturday as more nations imposed restrictions on travel from southern Africa.

New Zealand has announced fresh measures from Sunday evening, Radio New Zealand reported.

Covid-19 Response Minister Chris Hipkins said late on Saturday that only New Zealand citizens will be allowed to travel into the country from the nine southern African nations, according to the news service.

Citizens would be required to stay in managed isolation for a full 14 days, as well as undergo testing, he was quoted as saying.

Australia early this month eased its international border restrictions for the first time during the pandemic, allowing fully vaccinated residents to return to the country without quarantine after higher vaccination levels.

Australia had largely stamped out infections for most of this year until an outbreak of the highly infectious Delta variant in late June spread rapidly across its east.

About 205,000 cases and 1,985 deaths have been recorded so far, lower than many other countries in the developed world.