Workers prepare frozen pipes during operations to construct an underground ice wall at Tokyo Electric Power Co.'s tsunami-crippled Fukushima Daiichi nuclear power plant in Fukushima Prefecture. Photo by Reuters/Kimimasa Mayama

Japanese authorities are looking into a case in which they believe that three Vietnamese trainees may have been tricked into working in areas affected by the Fukushima nuclear disaster that took place in 2011.

The three men arrived in Japan in 2015 on a Technical Intern Training Program as trainees at a construction company in Koriyama City, before being posted on a radiation cleanup program in Fukushima Prefecture between 2016 and 2018 , Japan Today cited the Zentouitsu Workers Union, which supports foreign trainees in Japan, as saying in a report on Thursday.

Japan rolled out the Technical Intern Training Program in 1993 with the aim of transferring skills to developing countries.

The contracts between the three men and the Japanese firm only said that they would be working on “formwork installation and reinforcing steel placements,” and did not give any detailed explanation of the decontamination work.

And these three men are not alone.

In March, a 24-year-old Vietnamese man who worked for a construction firm claimed he was tricked into radioactive cleanup work in Fukushima, and asked for compensation from his employer.

The Zentoitsu Workers Union said the man was supposed to have been assigned to public engineering work, but was instead moved to work in contaminated areas in the prefecture, which exposed him to radiation.

The man, who wishes to remain anonymous, said he was not informed he would be cleaning up areas contaminated after the nuclear disaster.

A major earthquake followed by a 15-meter tsunami disabled the power supply to three Fukushima Daiichi reactors on March 11, 2011, causing a nuclear accident with high radioactive releases that forced tens of thousands of people to flee from their homes. Only a small number of them have returned.

The company, however, denied the man’s allegations in an interview with Nikkei, saying that he was assigned to duties that did not expose him to any health threats.

The incident sparked fury over Japan’s trainee program, which many said had been designed to help foreign nationals to acquire technical skills but instead had been exploited to make up for the shortage of unskilled workers in Japan.

Japanese Minister for Reconstruction Masayoshi Yoshino said that “this is something outrageous and totally illegal."