NSW’s quarantine rules for international airline crew are in the spotlight after being revealed as the likely source of the state’s latest COVID- 19 scare.

NSW recorded no new locally transmitted cases overnight, with two new cases detected in people returning from overseas travel.

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There are 78 active cases of the virus across NSW.

The state has almost reached 30 days without a locally transmitted case but the record nearly collapsed on Friday amid concerns the hotel worker had contracted the virus in the community.

Genome sequencing on Friday confirmed that the infected Sydney quarantine hotel cleaner contracted the virus at work.

“The viral genome sequence from the recent COVID-19 case who works at a Sydney quarantine hotel complex does not match the virus strains seen in recent clusters in Australia,” Saturday’s statement read.

“The virus may be of US origin. The source of infection may be international aircrew who were self-isolating in the hotel at the time, however investigations are continuing.”

Airline crews from overseas stay in quarantine hotels between flights and state and federal authorities are working to try and identify the crew member, who might have since left Australia.

Testing of the woman’s contacts is continuing but there have been no further positive results so far.

NSW Health says anyone who travelled on the same rail services as an infected hotel worker should get tested for COVID-19.

Those who shared a train carriage with the woman are deemed close contacts and have been asked to isolate for 14 days from their potential exposure.

A full list of affected train services and carriages is available on the NSW Health website.

The infected woman’s diagnosis sparked widespread alarm on Thursday, with fears Western Australia could withdraw its promise to open its border up to NSW and Victoria from next Tuesday.

WA Premier Mark McGowan says he will take the weekend to consider the situation.

However, Queensland authorities say its borders will remain open for now after travel restrictions were lifted on Tuesday.

Queensland recorded two new cases of coronavirus in hotel quarantine.

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Elsewhere, Victoria recorded 36 consecutive days without a new COVID-19 infection, with 7,670 test results were conducted in the past 24 hours.

The latest figures come as Premier Daniel Andrews is expected on Sunday to announce further relaxation of coronavirus restrictions.

-with AAP