Thailand liberated 68 fishermen who had been left to work under slave-like conditions on vessels in the eastern part of the Indonesian archipelago, media reported on Friday.

An air force C130 plane arrived at Don Muang Airport in Bangkok on Thursday carrying the rescued fisherman, many of whom were sold into human trafficking and were working on Ambon, Benjina, Dobo and Tuan islands.

According to the authorities, many of the boats conscripted Thai, Burmese and Lao fishermen for illegal fishing activities.

“It was unbelievably hard work. On occasions I had to work without sleep for one week,” Phongsathon Bunon, a 19-year-old rescued fisherman, said.

The young man recounted that he had willingly gone to work on a fishing boat at the age of 13, but was unaware of the harsh work conditions and that he would not be able to return home.

Watchdog organizations like Human Rights Watch have repeatedly denounced the practices committed by several fishing boats in Southeast Asia, which often amount to exploitation and even murder.