Thai authorities have arrested 433 Cambodian migrants in a two-day operation for crossing the border illegally to work. Police and military personel carried out the raids on Thursday and Friday, officials revealed.

“All of them have been sent back through the Poipet border,” said Neth Serey, Cambodia’s general counsellor in Sa Kaeo, adding that 327 migrants were picked up on Friday.

“Thai authorities checked on whether they had legal documents and none of them had any. So they were sent back across the border and they [the Thais] informed us.”

Thousands of migrant workers have returned to Thailand in the past three weeks after a mass exodus saw nearly 250,000 Cambodians pour across the border in June. This was triggered after Bangkok’s military government announced a crackdown on illegal labour.

While most Cambodian workers are using a new fast-track system to return to Thailand legally, others have relied on illegal brokers to get back into the country.

“No one can cross illegally through [our] checkpoint but they are going through illegal checkpoints and they are being sent back through ours,” said Sim Sam Ath, Poipet immigration police chief.

According to the Bangkok Post, the arrests on Friday were made by police and military officers during three separate operations in Aranyaprathet district.