Thai authorities have announced that they are launching renewed efforts to document illegal migrant workers across Thailand, in what observers say is part of a continuing crackdown on unregistered migrants there, an estimated hundreds of thousands of whom come from neighbouring Cambodia.

Arak Phrommanee, head of the Department of Employment, said that staff from his department would begin a nationwide search through industrial zones for illegal migrants. Migrant workers caught without proper work permits, he said, would face harsh punishments, though he did not specify what those would be.

Employers caught harbouring unregistered migrants risked having their businesses shuttered. They could also be fined $2,800 per worker, with fines as high as $11,215 per worker in the fishing industry.

Thailand has faced stiff international criticism for its atrocious regulation of migrants working at sea, some of whom have been trafficked into slavery. The Thai cabinet on Tuesday decided to extend a registration period for Burmese, Laotian and Cambodian workers in the fishing industry until the end of July.

Andy Hall, a migration expert and activist based in Thailand and Myanmar, lambasted the recent announcement as another instance of “schizophrenic short-term face-saving policies” from Thai officials.

“It’s out of control to be honest. They don’t know what they’re doing. There’s no long-term policy. There’s no planning. It’s just these announcements again and again. It’s not really realistic,” he said.

Hoya Dethy, a labour officer at Phnom Penh rights group CENTRAL, said that while migrant workers should in principle register legally in Thailand, the process to do so was often too costly for Cambodian migrants, many of whom were often extorted by employers to obtain registration, being charged fees ranging from $300 to $500 for a single worker.

For workers apprehended by authorities working illegally in Thailand, Dethy painted a grim picture.

“They might put them in jail, but some extort money or starve them. This is what I’ve heard from victims of illegal migration to Thailand,” he said.

Thai government pressure on its 1.6 million migrant worker population has caused voluntary repatriations in the past.

Thailand’s coup in May 2014 triggered a mass exodus of workers back to Cambodia after rumours spread that the military was launching a tough crackdown on illegal labour.

Cambodia’s Ministry of Labour could not be reached for comment.

Additional reporting by the Bangkok Post