Japan has brushed off London's offer to host the 2020 Olympics if the outbreak of the coronavirus forced the games to be moved from Tokyo, insisting the games would open as planned on July 24.

"We will move forward preparations for hosting a safe and secure Olympics," Japan's Chief Cabinet Secretary Yoshihide Suga was quoted as saying by Tokyo-based Kyodo News at a press conference on Friday morning.

The assurance comes as a response to an offer from London's mayoral candidate Shaun Bailey for the Conservative Party, proposing to take over the Olympics. The proposal was later supported by Mayor Sadiq Khan.

"London can host the #Olympics in 2020," Bailey tweeted on Wednesday.

"Given the ongoing disruption caused by the coronavirus outbreak, I urge the Olympic Committee to seriously consider how London could stand ready to host the Olympics should the need arise," Bailey said in a statement.

"We have the infrastructure and the experience, and if I am elected I will make sure London is ready to host the biggest sporting celebration again if we are called on in an hour of need," he said.

CBS reports a spokesperson of the London Mayor said in a statement they're willing to do it if the "unlikely" opportunity presents itself.

"Everyone is working towards what will be a fantastic Tokyo games. In the unlikely event that it is required, London, as it has done throughout history, will do its best to step up to the plate."