Krystsina Tsimanouskaya, 24, had been due to compete in the women's 200 meter heats on Monday (August 2) but said the Belarusian head coach had turned up at her room on Sunday (August 1) at the athletes' village and told her she had to leave after she had criticized team officials.
"I will not return to Belarus," she told Reuters at the time.
IOC spokesperson Mark Adams told a news conference that it had received a report from the Belarus NOC and was currently evaluating it.
Tsimanouskaya left Tokyo for Austria on Wednesday, after previously having been scheduled to board a flight to Warsaw, where the Polish government has offered her a humanitarian visa.
A member of the Belarusian community in touch with Tsimanouskaya said diplomats had changed her flight due to security concerns.