The department said in a statement that the 23-year-old was not being held and that arrangements were being made for her to be able to board a flight from Thailand.
Nuit Itsaragrisel, the founder of the Miss Thailand International pageant, who also represents Han Lai, said she had been in the transit area of Bangkok’s airport since Wednesday afternoon.
He said Han Lai was stopped upon arrival because she was the subject of an Interpol notice.
“She doesn’t want to go anywhere else. She wants to live in Thailand,” he told Reuters. “She is waiting for a solution on how to stay in Thailand.”
Myanmar has been in crisis since a coup in February last year sparked protests, which the army put down with lethal force and thousands of arrests.
A spokesman for Myanmar’s ruling military council could not be reached for comment. Interpol did not immediately respond to a request for comment on whether Han Lai was the subject of an Interpol notice.
Han Lai was a Miss Grand International contestant when videos went viral on social media showing her battling tears on stage as she spoke about the bloodshed in Myanmar, on a day when more than 140 protesters were killed.
She said in an interview with Reuters last year that her people “will never give up”.
Han Lay’s Instagram posts indicate that she has spent most of the past year in Thailand. She was returning home on a flight from Vietnam when she was denied entry.
Additional reporting by CNN’s Heather Chen.