BANGKOK: The dramatic departure of nearly 190,000 Cambodian migrant workers from Thailand threatens to hit labour-intensive industries hard, from seafood to construction, inflicting damage on the Thai economy just as it teeters on the verge of recession.

Panicked labourers - who help keep major Thai businesses afloat but often lack official work permits - have fled in droves, fearing a crackdown by the new military junta after it warned illegal migrants face arrest and deportation.

Despite officials from both countries denying a clampdown is under way, rumours of violent anti-immigration raids have spread across Thailand, where businesses already report feeling the pinch of a shrinking workforce.

In Rayong province, around 200 kilometres from the Thai-Cambodian border, factories have cut production after losing many of their Cambodian workers, said Sanguan Seangwongkij, vice chairman of the association of rubberwood operators in the region.

"Many of the factories in my group have had to slow down production because of an up to 30 per cent shortage of workers," he said, adding it was "damaging foreign confidence" in the sector.

The factories, which process old rubber trees to make furniture, rely upon Cambodian labour but also hire workers from Myanmar, he explained.

Thailand has around 2.3 million legal migrant employees and a further 800,000 are thought to be working illegally, according to the employment department.

The latter is a conservative estimate, according to the International Organisation for Migration.

The kingdom has virtually no unemployment and depends upon neighbouring Cambodia, Laos and particularly Myanmar - where the majority of Thailand's migrants come from - to fill vacancies. AFP