BANGKOK — Tens of thousands of migrant workers, most of them from Myanmar, have fled from Thailand in fear after new labor regulations adopted by the military government, immigration officials said on Monday.

Industry groups said the exodus was already hitting some companies, which depend on migrants from Thailand’s poorer neighbors for manual labor for everything from construction to the multi-billion dollar seafood industry.

“The private sector is in shock,” said Tanit Sorat, vice-chairman of Employers’ Confederation of Thailand. “These are jobs that Thais will not do so if there is a labor shortage businesses cannot move forward.”

Thailand has more than three million migrant workers, the International Organization for Migration says, but rights groups put the figure higher.

Since taking power in a 2014 coup, Thailand’s ruling junta has had varying degrees of success in campaigns to regulate the foreign work force, spurred partly by media reports that unregulated workers faced exploitation by employers.

About 60,000 workers left between June 23 and June 28, and the number has risen since, an Immigration Bureau official said.

“They were of all nationalities, but the biggest group was from Myanmar,” Deputy Commissioner Pornchai Kuntee told Reuters. “They are probably very scared.”

Following news of the exodus, Thailand on Friday promised a 120-day delay in enforcing parts of the decree, including fines that can range up to 800,000 baht ($23,557) for employers who hire unregistered foreign workers without permits.

Geta Devi, 28, a worker from Myanmar based in Bangkok, said some of her friends panicked over the decree and headed home.

Thai government trucks have been taking workers to the Myanmar town of Myawaddy, 246 km (153 miles) east of Yangon, and opposite the Thai town of Mae Sot, a Myanmar official said. It was unclear if they were leaving Thailand voluntarily.

More than 16,000 people, including both legal and undocumented migrants had returned since June 29, said Aung Htay Win, a labour ministry official who is coordinating Myanmar’s response. Returning workers were being temporarily housed in government buildings.

“Most of them stay for one night or so, then they continue to their home towns,” he said,

Up to 500 migrant workers had returned to Cambodia since last week, authorities there said.

In Bangkok, an executive at a construction company said as many as 80% of workers had gone from some of its building sites.

Fishing groups also voiced concern, saying foreign workers were essential for nearly 30,000 boats.

“If foreign labour disappears, these boats will remain docked,” said Mongkol Sukjareonkhana, chairman of the Thailand Fishery Cooperative.

But Thai Union, the world’s biggest canned tuna company, told Reuters it expected no impact because all its migrant workers were legal.

Agribusiness giant Charoen Pokphand Foods also said none of its workers had gone home.

There was little change on Monday in the prices of their shares or those of Thailand’s three biggest listed building firms: CH Karnchang, Sino Thai Engineering and Italian Thai Development.

Mass movement leaves undocumented workers vulnerable, said Andy Hall, a migrant workers’ rights expert who has monitored migration in Thailand for more than a decade.

Despite a police threat of punishment for anyone trying to extort money from migrants or employers, “corrupt officials” would try to seek bribes, he told Reuters.

“Mass profit is to be made in a short time from the panic and commotion,” Mr. Hall said.

Last month, the United States kept Thailand on a trafficking watch list, saying it fell short of the minimum standards to end human trafficking. Thailand defended its anti-trafficking efforts, urging US officials to visit and assess them. — Reuters

This Sept. 1, 2016 photo shows workers unloading goods from trucks behind Hua Lampong train station in Bangkok. — AFP