Australia's Olympic athletes have been told to plan for the Games to be delayed until next year.

Key points: The Australian Olympic Committee (AOC) said an Australian team "could not be assembled in the changing circumstances"

The Australian Olympic Committee (AOC) said an Australian team "could not be assembled in the changing circumstances" Chef de Mission Ian Chesterman said "it's clear" the Games can't be held in July

Chef de Mission Ian Chesterman said "it's clear" the Games can't be held in July Canada's Olympic Committee said it would not send athletes to the Olympics or Paralympics

The move came after Canada's Olympic Committee said it would not send athletes to the Tokyo Olympics, currently scheduled for July.

"Australian athletes should prepare for a Tokyo Olympic Games in the northern summer of 2021," the Australian Olympic Committee (AOC) said in a statement.

It said the Australian team "could not be assembled in the changing circumstances at home and abroad".

This latest announcement was made after the International Olympic Committee (IOC) said it needed four weeks to decide on whether to postpone the Games or not.

Just last Thursday, the AOC said that the IOC was not entertaining the idea of a postponement and that a decision on the Games did not need to be made immediately.

AOC chief executive Matt Carroll said the decision gave athletes certainty about the situation.

"We have athletes based overseas, training at central locations around Australia as teams and managing their own programs," Mr Carroll said in the AOC statement.

"With travel and other restrictions this becomes an untenable situation.

"The IOC had adopted the key principles of putting athlete health first and ensuring it acted in their best interests and the interests of sport. This decision reflects those principles.

"We are now in a position where we can plan with greater certainty."

The AOC said an Australian team "could not be assembled". ( AAP: Dean Lewins )

Mr Carroll thanked the athletes' representative, Olympic gold medallist Steve Hooker, for communicating the views of the athletes.

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Australia's Tokyo chef de mission Ian Chesterman said on Thursday that the majority of athletes wanted to go to the Games in July.

However, after receiving feedback from athletes from over 25 sports last week, Mr Chesterman said: "It's clear the Games can't be held in July.

"Our athletes have been magnificent in their positive attitude to training and preparing, but the stress and uncertainty has been extremely challenging for them," Mr Chesterman said.

"They have also shouldered the burden of concern for their peers around the world. That has been a consistent message to me.

"While there will still be much to work out as a result of this change, the timing will allow athletes from around the world to properly prepare with the hope the coronavirus crisis will be under control.

"We are aware that for many such a postponement will present a range of new issues. But when the world does come together at the Tokyo Olympic Games, they can be a true celebration of sport and humanity."

Olympic gold medallist Jared Tallent told the ABC it was a relief athletes finally had some certainty.

"It was getting to the stage where a lot of athletes were struggling to find places to train, and worrying about if they should be going to training with all the government advice that had been going around," Tallent said.

"It's good that this announcement has happened and it will reduce a lot of anxiety and stress that athletes had been feeling over the last couple of weeks."

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 1 minute 41 seconds 1 m 41 s Gold medallist says it's a "relief" to have certainty over the Olympics

Tallent said he hoped the Games would be rescheduled, rather than cancelled completely.

"Every athlete wants the Games to go ahead at some stage and it would be pretty devastating if they were to be cancelled," he said.

"I was planning to retire after Tokyo. This was going to be my fourth Olympics. I'd been training for four years for this, so for it to be cancelled would be devastating.

"Now I'll push on for another year hopefully, if it goes ahead in 2021."

Earlier, the Canadian Olympic Committee said it would not send athletes to the Games this year, issuing an "urgent" call for the event to be postponed for 12 months.

"While we recognise the inherent complexities around a postponement, nothing is more important than the health and safety of our athletes and the world community," the committee said.

There are growing calls to postpone the Games in the face of the coronavirus pandemic, with Japanese Prime Minister Shinzo Abe saying postponing the Games may be an option.

On Sunday, the IOC said a cancellation was "not on the agenda."