Thousands of migrant workers across Thailand have been arrested after Thai prime minister Abhisit Vejjajiva ordered police to intensify a crackdown on illegal workers, although reports have emerged that even those holding work permits were rounded up.

It follows the creation by Vejjajiva of a governmental centre tasked with “suppressing and prosecuting” illegal migrants, the vast majority of whom are Burmese.

Thailand has also set in motion a scheme aimed at persuading migrant workers to return to their home countries to register for legal status, before re-entering Thailand to work.

Those eligible were required to register their intention to take part in the scheme in February this year, and rights groups have said that the latest crackdown has targeted those who did not comply, along with some who were already carrying permits. One group told DVB that Thai police were also profiting from the crackdown.

“Recently in Tala Tai near Bangkok, two markets where Burmese nationals worked at were raided and about 600 people were arrested,” said Sein Htay of the Thailand-based Human Rights and Development Foundation (HRDF).

He said that half of those arrested were Burmese. Thailand is home to more than three million migrant workers, and around 80 percent are thought to be from Burma.

“Some people had the migrant labour cards but they were still arrested. When their bosses didn’t collect them [from the police] they get sent to the border along with the illegal migrants,” Sein Htay added.

He warned that police extortion of migrants was rife, with many forced to pay bribes before being released. One Burmese migrant worker in the Thai border town of Ranong told DVB that army troops had showed up in recent days.

“For around four days people have been afraid to go outside and work due to the increase in arrests. The workers supported by their bosses can go out no problem but otherwise they can’t. There are more workers without labour cards than with.”

Police bribes can be as much as 6000 Thai baht ($US185), the man said, well beyond the reach of most migrant workers who often earn less than half of Thailand’s 206 baht ($US6) per day minimum wage.

He added that meeting the fees for the nationality verification process was also unrealistic. “We didn’t apply [for the permits] as we have four people in our family and it will cost about 15,000 baht [$US460] to apply for three of us. We don’t have that amount of money and no one will lend it to us either.

A statement issued on Monday by HRDF urged the Thai government to halt the crackdown. Some 90,000 Burmese migrants have so gained the permits out of a total of 800,000 that have enrolled in the process.