The International Olympic Committee (IOC) is coming under increasing pressure to postpone the 2020 Tokyo Olympics until next year.

The latest and most significant call for a cancellation of the Summer Games this year, due to the COVID-19 outbreak, has come from USA Track and Field (USATF).

USATF chief executive Max Siegel penned a letter to the US Olympic and Paralympic Committee asking them to request a change of dates for the Tokyo Games which are due to get underway on July 24.

IOC president Thomas Bach gave an interview to German broadcaster SWR last week in which he insisted that, "a cancellation is not on the agenda."

That's despite the cancellation of sports events all around the world but Bach added in the interview:

"You cannot postpone the Olympic Games like a football match next Saturday," said Bach.

"This is a very complex company, where you can only act responsibly if you have reliable and clear bases for decision-making, and we observe them every day, 24 hours a day."

The Japanese government is also refusing to admit defeat just yet with a top government spokesman saying as recently as last Wednesday that Tokyo wasn't preparing for postponement.

However on Sunday the Reuters news agency reported that Tokyo 2020 organisers have started to draft possible alternatives to holding the Olympics this summer.

Reuters quote two sources who requested anonymity as they are not authorised to speak to the media.

"Finally, we have been asked to make a simulation in case of a postponement," said one of the sources.

"We are making alternative plans - plan B, C, D - looking at different postponement time-frames," said the official, adding the scenarios included cost estimates for different delays.

The official also said that options include scaling back the Games or holding them without spectators and that options will be debated at the end of March.

The second source, who Reuters say is also close to the Tokyo 2020 organising committee, confirmed the postponement is being discussed, including delays of one or two years.

The summer 2021 is already looking crowded while the Beijing Winter Olympics and the soccer World Cup are due to take place in 2022.