All 92 Singapore residents who were evacuated from Wuhan on a specially arranged Scoot flight last Thursday are being tested for the coronavirus, and four so far have tested positive.

Two Singaporeans who flew back last week were among the six new confirmed cases announced yesterday.

The Ministry of Health (MOH) said both tested positive for the virus on Monday despite not showing any symptoms.

They are now warded in isolation rooms at the National Centre for Infectious Diseases (NCID).

The ministry's director of medical services, Associate Professor Kenneth Mak, said during a press conference yesterday that the pair were quarantined upon landing in Singapore.

"They have remained in quarantine since their return to Singapore, so there's no risk of any spread to any other individual," he noted.

Prof Mak said the ministry began testing the 92 passengers as they had a higher risk of infection given the community spread in Wuhan.

Those who did not have symptoms were also tested to see if asymptomatic travellers could carry the virus, Prof Mak added.

Two other Singaporean women on the flight, both 47, were previously confirmed to be infected on Friday and Saturday.

They were found with fever upon their return and were taken to the NCID.

All four were asymptomatic when they boarded the flight. Temperature screening was conducted at check-in and before the passengers boarded, and those found to be running a fever were not allowed to board.

It is currently unclear if the four had any close contact or interacted with one another, Prof Mak said.