Hundreds of Americans have been flown out of Japan after leaving the quarantined Diamond Princess cruise ship on Sunday night, as a further 70 people onboard tested positive for Covid-19, bringing the total to 355.

The removal of US citizens from the ship, moored at Yokohama, south of Tokyo, came as other countries said they would fly their citizens home just four days before the official quarantine set by Japanese health authorities was set to end.

Passengers wearing masks could be seen waving through the windows of buses parked near the ship.

The US evacuation began hours after China’s national health commission announced the death toll from the coronavirus inside the country had risen to 1,765, with at least 70,400 infections. It follows a spike last week when Hubei province changed the way it was counting cases of the virus.

US officials said 380 Americans would be taken to an air force base in California on two government-chartered aircraft leaving Tokyo’s Haneda airport on Monday.

About 40 US citizens onboard the ship have tested positive for the virus and will be treated in Japan. Those displaying symptoms will not be allowed to board the plane.

The Diamond Princess, with about 3,500 passengers and crew onboard, has the highest number of coronavirus infections outside China. Those testing positive will be transferred to Japanese hospitals.

If infections on the Diamond Princess are included, Japan, with 404 cases, has the third highest number of Covid-19 infections outside China’s Hubei province, where the illness is thought to have originated. The city of Wenzhou, in Zhejiang province, has 502 recorded cases, followed by Shenzhen, in Guangdong province, with 414 cases.

Japan’s health minister, Katsunobu Katō, told public broadcaster NHK: “We must anticipate a spread of infections from now and must build a medical system to focus efforts to prevent people from becoming gravely ill or dying.”

The US embassy in Tokyo said passengers and crew onboard the ship were at high risk of exposure to the virus and it recommended its citizens take one of the flights home.

It said all passengers would be screened before being allowed to board the chartered flights and everyone would be quarantined for 14 days upon arrival.

Gay Courter, one of the American passengers onboard, said: “Leaving in a few hours. No details. Might be going to Texas or Nebraska.”

Kyodo news agency quoted Takaji Wakita, the head of the National Institute of Infectious Diseases, as telling reporters:“We agreed that the present situation represents the early stage of a domestic outbreak. This could progress further.”

South Korea’s government, meanwhile, said it would join the US in removing its citizens from the Diamond Princess. “The government plans to bring those Koreans home if they are tested negative from screenings by the Japanese authorities and are willing to return,” the minister of health and welfare, Park Neung-hoo, said.

About 68,500 people in mainland China have been confirmed to have been infected with the coronavirus, and 1,665 people have died from Covid-19, China’s national health commission said on Sunday. The figures included a further 142 in the 24 hours to midnight on Saturday, and a further 2,000 new confirmed cases.

Facebook Twitter Pinterest Jumbo jets at Haneda airport arrive in Tokyo ready to evacuate US citizens from the Diamond Princess cruise ship. Photograph: Kazuhiro Nogi/AFP via Getty Images

Matthew Smith, an American passenger who chose to remain on the ship, said rows of buses had appeared ready to take evacuated passengers to Tokyo’s Haneda airport on Sunday evening.

“The fleet of coaches – 11 in all it appears – lined up to ‘save’ the Americans. An American woman – who last night could be heard shouting, ‘Get me off this ship’ – stands on her balcony chanting ‘USA, USA’. Of course, in contravention of the rules of quarantine, she’s not wearing a face mask, & she’s talking with a passenger on the adjacent balcony well within 6 feet of each other,” Smith tweeted.

“We scurry back inside. If there are secondary infections onboard, this is why: idiots who don’t know any better. And you wanted me to get on a bus with her?”

Q&A How can I protect myself and others from the coronavirus outbreak? Show Hide The World Health Organization is recommending that people take simple precautions to reduce exposure to and transmission of the coronavirus, for which there is no specific cure or vaccine. The UN agency advises people to: Frequently wash their hands with an alcohol-based hand rub or warm water and soap

Cover their mouth and nose with a flexed elbow or tissue when sneezing or coughing

Avoid close contact with anyone who has a fever or cough

Seek early medical help if they have a fever, cough and difficulty breathing, and share their travel history with healthcare providers

Advice about face masks varies. Wearing them while out and about may offer some protection against both spreading and catching the virus via coughs and sneezes, but it is not a cast-iron guarantee of protection Many countries are now enforcing or recommending curfews or lockdowns. Check with your local authorities for up-to-date information about the situation in your area. In the UK, NHS advice is that anyone with symptoms should stay at home for at least 7 days. If you live with other people, they should stay at home for at least 14 days, to avoid spreading the infection outside the home.

Japan’s health ministry said on Saturday that passengers older than 70 were being examined and those testing negative and in good health would be allowed to leave the ship from Wednesday.

Hong Kong, which has 330 citizens onboard, said it would offer nationals an evacuation flight. The Canadian government also confirmed late on Saturday that it had chartered a plane to bring back its citizens.

Canadian passengers who exhibit symptoms of the coronavirus infection will not be permitted to board the flight and will instead be transferred to the Japanese healthcare system to receive appropriate care, the government said.

The Diamond Princess has been stuck in Japan after a passenger who had disembarked in Hong Kong at the end of last month tested positive for the virus.

The Australian embassy in Tokyo emailed its citizens onboard the cruise ship to say the federal government was also examining options to assist them. The embassy told them it understood it was a “very stressful” situation for them and that Australian medical officers were working closely with Japanese authorities to support them.

The British government has faced mounting pressure to evacuate its citizens, with one passenger, David Abel, who had been livestreaming from the ship, saying on Saturday that he had “given up on anybody in the UK”.

Passengers on the Diamond Princess have been mostly confined to their cabins since 3 February, after measures were introduced to try to stop the spread of the disease onboard. The quarantine is due to end on Wednesday, though it is not clear if the emergence of fresh cases will prompt such restrictions to be extended.

There is also growing concern over possible infections among people who disembarked from the MS Westerdam in Cambodia on Friday, after it was confirmed that one passenger, who later flew to Malaysia, tested positive for the virus.

The 83-year-old woman flew from Cambodia to Malaysia on Friday with 144 others from the ship. The woman’s husband tested negative for the disease, Malaysia’s health ministry said.

The ship had been turned away by five countries, despite having no reported sickness onboard at the time.