She has claimed that she was being "forced" to return home after criticising national coaches.
Krystsina Tsimanouskaya has received a humanitarian visa by Poland after
refusing to board a flight home to Belarus.
She was seen entering the Polish embassy in Tokyo on Monday morning, having spent the previous night at an airport hotel.
The 24-year-old Belarusian sprinter said she was seized by officials from her own country on Sunday after she publicly complained about the national coaches.
Belarus has claimed that she was ordered to return home due to her "emotional condition."
Poland had offered to help Tsimanouskaya, with deputy foreign minister Marcin Przydacz tweeting that Tsimanouskaya "has received a humanitarian visa".
He added: "Poland will do whatever is necessary to help her to continue her sporting career."
https://twitter.com/marcin_przydacz/status/1422146358958596100
Her arrival at the Polish embassy come after France's European affairs minister said it would be an "honour" if Europe were to grant her political asylum.
Meanwhile the US Ambassador to Belarus tweeted: "Thanks to the quick action of Japanese and Polish authorities, Tsimanouskaya is able to evade the attempts of the Lukashenka regime to discredit and humiliate this #Tokyo2020 athlete for expressing her views. #StandWithBelarus."
https://twitter.com/USAmbBelarus/status/1422154475431763971
The Belarusian Embassy in Tokyo has made an official request to the Japanese authorities for information about the athlete, the RIA news agency reported.
Tsimanouskaya had been due to compete in the women's 200 metres and the 4x400 metres relay at the Tokyo Olympics this week.
But after her inclusion in the relay team, she criticised team officials in a message on her Instagram, pointing out that she had never taken part in the event before. She also claimed some members of her team were judged ineligible to compete because they had not undergone enough doping tests.
In a statement on its Facebook page, the Belarus Olympic Committee said Tsimanouskaya was removed from the Games because of her "emotional and psychological state".
It said: "According to doctors, due to the emotional and psychological state of the Belarusian athlete Krystsina Tsimanouskaya, the coaching staff of the national athletics team decided to stop the performance of the athlete at the XXXII Olympics.
"Consequently, the athlete's application for participation in qualifying races at 200m and in the 4x400m relay was recalled."
