A large group of Australians stranded on a cruise ship in Japan for a fortnight while the deadly coronavirus spread through its passengers have arrived back in Darwin.

Some 180 citizens and permanent residents had taken up the federal government’s offer of a seat on the evacuation flight, which left Haneda Airport near Yokohama early on Thursday (local time).

But 10 were told they could not leave because they had tested positive to the deadly disease, known as COVID-19. That meant only 170 could board the Qantas flight.

Another 15 had already chosen to stay behind in Japan to be near family members who have been hospitalised after contracting the virus. They included a Melbourne family whose daughter tested positive just hours before the plane was due to leave Japan.

Tweet from @qtiepie

Melbourne mum Aun Na Tan said the family was initially distressed at daughter Kaitlyn’s diagnosis.

“It wasn’t a pretty picture when we first found out but I think we’ve looked at everything, we’ve had lots of wonderful messages come to us, a flood of them from family,” Ms Tan told Nine’s Today show on Thursday.

“It will be good. She’ll be right.”

The Qantas Boeing 747 jet carrying the other evacuated Australians landed in Darwin at 9.41am (AEDT).

• Related: Positive tests thwart evacuation plans

Once they had disembarked, the Australians were to be screened for symptoms of the virus five times before being taken to a former workers’ camp at Howard Springs, 30 kilometres south-east of Darwin.

The evacuees have already spent more than two weeks quarantined on Diamond Princess in Yokohama port. They now now face another 14-day isolation period at the former Inpex camp.

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The number of confirmed cases of coronavirus on the ship, which was carrying 3700 passengers and crew, has topped 620 and includes 36 Australians.

Australia’s deputy chief medical officer Paul Kelly said while the ship’s quarantine methods had worked to stop the virus spreading onshore, there had been a recent spike in cases on board.

“It just demonstrates the infectiousness of this particular virus and how it can spread very easily in a closed setting like a cruise ship,” he said.

The cruise ship evacuees will be kept separate from hundreds of people already in quarantine at Howard Springs. They were evacuated from the epicentre of the virus at Wuhan, the capital of China’s Hubei province earlier in February.

Meanwhile, Australia is expected to extend its China travel ban for another week amid ongoing fears about the spread of the virus, locking out Chinese students and tourists.

“We’re going to take the best advice of our medical experts,” Treasurer Josh Frydenberg told Sky News on Thursday.

“It’s had a significant economic impact but we’re doing these protectionist measures to ensure that we protect the Australian people.

“These are precautionary initiatives that we have taken.”

More good news that today the next group of more than 30 people we helped get out of Wuhan left Christmas Island to head home, the last of those who were quarantined there. All of them have been declared free of Coronavirus. pic.twitter.com/SrYvQIflTB

— Scott Morrison (@ScoMo30) February 19, 2020

Elsewhere, all of the evacuees on Christmas Island have left the detention-centre turned-quarantine-facility.

None have tested positive for the coronavirus.

There have been 15 confirmed cases of the disease in Australia. Eight people recovered and the rest are in stable conditions.

So far there have been more than 75,200 cases worldwide and 2009 people have died. Almost all of the deaths were in China.

-with AAP