Some 20 ethnic Uighur Muslims from China are on the run after escaping from a Thai detention centre, the BBC quoted officials as saying on Monday.
The inmates were among a group of more than 200 Uighurs detained in 2014.
Officials said 25 inmates dug holes in cell walls and used blankets to climb over the jail's barbed wire near the Malaysia border. Five have been caught.
Hundreds of Muslim Uighurs have left their home region of Xinjiang in recent years alleging oppression.
The dramatic overnight escape happened in southern Songkhla province, immigration officials said. The inmates used broken tiles to dig through their cell walls.
"Twenty are still at large," a senior police official at the detention centre said. "Heavy rain helped to mask the loud escape noises."
He said checkpoints had been set up along the border.