A Melbourne family has missed an evacuation flight to Darwin after spending two weeks trapped on a coronavirus-riddled cruise ship because their daughter tested positive hours before the plane was due to leave Japan.

About 170 Australians stuck on the Diamond Princess cruise were expected to board a government-chartered Qantas flight in the early hours of Thursday morning, but at least one family will have to stay behind and be taken to hospital in Japan.

Melbourne mum Aun Na Tan with family aboard the Diamond Princess cruise ship. Credit:Aun Na Tan

Melbourne mum Aun Na Tan said her daughter Kaitlyn tested positive for the virus just hours before the flight was leaving Tokyo for Darwin, where passengers will spend another two weeks in quarantine at a mining camp.

The rest of the family was cleared of the virus. Because Kaitlyn is a minor, the family was given the option of having just one parent stay back, but they insisted on staying together in Japan.