Olympic officials said Tuesday they will investigate Belarus over claims the team tried to force an athlete now sheltering in Poland's Tokyo embassy to return home after she criticised her coaches.

Krystsina Tsimanouskaya says she fears for her safety if she returns to Belarus, and she is expected to travel to Poland this week after being offered a humanitarian visa.

US Secretary of State Antony Blinken on Tuesday accused Belarus of an "act of transnational repression" over the alleged attempt to force her home.

Olympic athlete Tsimanouskaya has said she fears for her safety if she returns to Belarus
Olympic athlete Tsimanouskaya has said she fears for her safety if she returns to Belarus Krystsina Tsimanouskaya/ESN / -

Tsimanouskaya spent the night in Poland's embassy in Tokyo after arriving there Monday evening. Warsaw has denounced what it calls a "criminal attempt" to kidnap the athlete.

Polish Prime Minister Mateusz Morawiecki said he had spoken to the "courageous" Tsimanouskaya, who is "currently well taken care of and safe".

"I assured her that she can count on the support and solidarity of Poland. In the coming days, she will fly to Warsaw, where she will be able to thrive without obstacles and, if she so chooses, will receive further assistance," he wrote on Facebook.

Tsimanouskaya's husband Arseny Zdanevich told AFP he had fled Belarus and was hoping to join his wife "in the near future".

The Belarusian was sheltering in the Polish embassy in Tokyo after being offered safe passage by Warsaw
The Belarusian was sheltering in the Polish embassy in Tokyo after being offered safe passage by Warsaw AFP / Yuki IWAMURA

"I believe it would not be safe for me to be there," the 25-year-old fitness trainer said by phone from Ukraine.

Tsimanouskaya, a 200 metres specialist, criticised the Belarusian athletics federation after they tried to force her to run in a relay. She said that outburst led to the attempt to forcibly send her home.

Belarus strongman Alexander Lukashenko has cracked down on any form of dissent since mass protests erupted after elections last year that were deemed unfair by the West.

The Belarusian was sheltering in the Polish embassy in Tokyo after being offered safe passage by Warsaw
The Belarusian was sheltering in the Polish embassy in Tokyo after being offered safe passage by Warsaw AFP / Yuki IWAMURA

Tsimanouskaya was one of more than 2,000 Belarusian sports figures who signed an open letter calling for new elections and for political prisoners to be freed.

Poland is a staunch critic of Lukashenko's regime and has become home to a growing number of dissidents.

Morawiecki said offering the athlete help was an important gesture "to get the word out on the international arena as to what is happening across our eastern border," telling Belarusians "we won't leave you stranded!"

The Polish embassy in Tokyo, where the athlete has taken refuge before flying to Warsaw
The Polish embassy in Tokyo, where the athlete has taken refuge before flying to Warsaw AFP / Yuki IWAMURA

Activist group Global Athlete called overnight for the IOC to immediately suspend Belarus's Olympic committee and allow the country's athletes to compete as neutral athletes.

The NGO said Tsimanouskaya's "alleged kidnapping... is yet another example of the alarming athlete abuse occurring in Belarus."

IOC spokesman Mark Adams said the body was launching a formal investigation and also expected to receive a report from Belarus's Olympic committee today.

"We're going to need to establish facts," he told reporters in Tokyo, adding that the IOC would "need to hear everyone involved."

Asked about the safety of the team's remaining athletes at the Games, Adams said IOC and Tokyo 2020 staff were based at the Olympic Village and could be approached if necessary.

The US secretary of state accused Lukashenko's regime of trying "to commit another act of transnational repression: attempting to force Olympian Krystsina Tsimanouskaya to leave simply for exercising free speech."

"Such actions violate the Olympic spirit, are an affront to basic rights, and cannot be tolerated," he tweeted.

Lukashenko, who has been in power since 1994, sparked international outrage in May by dispatching a fighter jet to intercept a Ryanair plane flying from Greece to Lithuania in order to arrest a dissident onboard.

Polish Deputy Foreign Minister Pawel Jablonski seemed to reference that incident when he declined to confirm whether Tsimanouskaya would fly out on Wednesday as has been rumoured, saying it was a safety matter.

"As we know, Alexander Lukashenko's regime has been known to resort to different methods, often straight up illegal ones," he told Polsat News.

The Olympic saga came as police in Ukraine said a missing Belarusian activist, whose NGO helps his compatriots flee the country, had been found hanged in a park in Kiev.