Foreign interns brought to Japan under its official job training program are being used to offset a shortage of construction workers in Kumamoto Prefecture, which is trying to rebound from the deadly earthquakes that struck in 2016.

But some people fear the interns are being exploited. A Filipino who was assigned to a local construction company has already sued over unfair treatment.

Japan launched the training program in 1993 as part of a purported campaign to transfer technical skills to developing countries. But the oft-maligned program, which covers vocations and skills ranging from carpentry and farming to caregiving and shucking oysters, has drawn fire over reports of harsh treatment and exploitation. It has often been called a cover for cheap labor.

Kumamoto, where tens of thousands of houses were flattened or damaged when two quakes struck in April 2016, subsequently saw a surge in so-called technical intern trainees that brought their number to about 4,500 in October 2017 from around 2,700 in 2015. The surge might be linked to already high demand for construction workers.

The process of rebuilding is making slow progress: Less than half of Kumamoto’s damaged roads and rivers have been rebuilt. And the number of construction-related jobs available, including building demolition and steel girder assembly, had doubled to 6.71 per job seeker in April compared with 2016, according to a local labor bureau.

A man who runs a construction company in the hardest-hit town of Mashiki said he was surprised to find subcontractors using so many foreign workers to take down buildings. He surmised that they were from Southeast Asia.

He said he had heard that foreign interns were being told to use dangerous heavy equipment despite being unlicensed to do perform such work.

In June, a Filipino technical intern sued a local construction firm and the group coordinating the internship program after he was ordered to undertake tasks that were not stipulated in his contract and after around ¥630,000 in overtime pay was withheld.

“It is difficult to know the actual working conditions of the trainees and trainees cannot easily raise their voices,” said Shinichiro Nakashima, who heads a Kumamoto-based support group for foreign residents of Japan. He said the government should keep close tabs on the issue.