US drugs giant Pfizer and its German partner BioNTech on Thursday announced a deal with the International Olympics Committee to provide vaccines to competitors and staff at the Tokyo games.

In a statement, the firms said they would coordinate with national sporting bodies to make sure that coronavirus vaccines are available to anyone who needs one before travelling to Japan.

"Delivery of initial doses to participating delegations is expected to begin at the end of May where possible with the aim to ensure participating delegations receive second doses ahead of arrivals in Tokyo," they said.

The agreement was welcomed by IOC president Thomas Bach, who has already seen the Tokyo Games postponed from last year because of the pandemic.

"We are inviting the athletes and participating delegations of the upcoming Olympic and Paralympic Games to lead by example and accept the vaccine where and when possible," Bach said.

There are expected to be more than 11,000 athletes at the games, which will run from July 23 to August 8, but many have already secured vaccines in their home countries.

The IOC has been promising for months that the Olympics would be safe even without widespread vaccination, thanks to a battery of health precautions.

The IOC has already said it will offer national delegations Covid-19 vaccines bought from China.

But the agreement with Pfizer is seen as important as Tokyo and several Japanese regions are once again under a state of alert due to the increase in cases of Covid-19, amid lingering doubts about the wisdom of holding the games.

Japan has already decided to ban spectators from abroad and the president of the organizing committee, Seiko Hashimoto, told AFP last Friday that the Olympics could be held behind closed doors for the first time in their history.

With Japan's hospital system already under intense pressure, Tokyo 2020 has been criticized for asking Japanese medical staff to work on the event, and Hashimoto said the absence of spectators could ease the pressure.

In an attempt to appease the skepticism of the Japanese public, organizers last week tightened the anti-virus measures imposed on both Olympic delegations and the media.

Albert Bourla, chairman and CEO of Pfizer and Ugur Sahin or BioNTech said their firms were proud to supply the vaccine -- already the mainstay of Europe's inoculation effort -- to the Games.

"The return of the Olympic and Paralympic Games represents a monumental moment of world unity and peace after a grueling year of isolation and devastation," Bourla said.

The firms noted that it would be a decision of individual countries' government whether to permit or require the vaccines be used, but added that the jab has been authorized by the EU, US, UK, Canada and other countries.