The chief executive officer of the Tokyo Olympics admitted Wednesday that organisers are "extremely worried" about the possible effect of the deadly new coronavirus on this summer's Games. Toshiro Muto said he hoped the outbreak in China would be quickly contained to restore confidence in the run-up to the Olympics.

"We are extremely worried in the sense that the spread of the infectious virus could pour cold water on momentum for the Games," he said before a meeting with the International Paralympic Committee (IPC).

"I hope that it can be eradicated as quickly as possible. We plan to cooperate with the IOC (International Olympic Committee), the IPC, the government and the city of Tokyo to tackle the disease."

Speaking to AFP, the IOC urged calm following Muto's comments.

"We have full confidence that the relevant authorities, in particular in Japan, China and the World Health Organisation (WHO), will take all the necessary measures to address the situation," said an IOC spokesperson.

"Preparations for Tokyo 2020 continue as planned."

More than 20 countries have confirmed cases of the pathogen, which has killed nearly 500 people and infected at least 24,000 in mainland China.

Japan has had no reported deaths so far, but at least 10 people on a cruise ship carrying 3,711 passengers and crew quarantined off Yokohama have tested positive for the new coronavirus.

Saburo Kawabuchi, the mayor of the Athletes' Village where an expected 11,000 sportsmen and women will stay, struck a sombre tone.

"I hope from my heart that we can overcome this (virus) and have a smooth Olympics," said the former Japanese football chief.

"We will do our everything we can to protect the athletes to allow them to produce their best performances." Tokyo governor Yuriko Koike promised at the weekend to implement "thorough measures" to protect people from the coronavirus in the run-up to the Olympics.