China began repatriating its citizens who worked in online fraud operations in Myanmar following a multinational crackdown on the centers dubbed by international groups as a nexus of human rights abuses and criminal activity.

About 200 Chinese citizens flew back to China on Thursday from an airport in Mae Sot, a town in Thailand’s Tak province that shares a border with Myanmar. They were flown on four separate flights after being transported by buses from Myanmar.

Hundreds more Chinese nationals will be sent back to the mainland over the next two days, Thai Defense Minister Phumtham Wechayachai said. Authorities from Thailand, China and Myanmar had worked together for over a month to plan for Thursday’s repatriation, and the three countries will meet again at a ministerial level in about a week about the next steps, he said.