Hong Kong’s anti-graft watchdog has arrested 148 people for allegedly using false documents to obtain job qualifications through bribery.

Ninety-one men and 20 women, aged 22 to 69, were among the suspects rounded up. Those detained included 100 excavator operators, 32 electricians and owners and employees of five engineering companies, as well as staff members of two training organizations approved by the Labour Department.

Responding to the operation by the Independent Commission Against Corruption, the Labour Department and the Electrical and Mechanical Services Department in charge of issuing such qualifications have revoked the licenses of the excavator operators and the electricians.

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In the case of the excavator operators, the ICAC said on Wednesday the masterminds ran an unaccredited machinery training school, claiming it could “guarantee success in examinations and obtaining professional certificates recognized by the Labour Department”.

It allegedly charged a “tuition fee” of about HK$22,000 ($2,820) to get inexperienced workers to take the dredger operation course.

Working hand in glove with engineering firms, the operator charged trainees sums of between HK$500 and HK$1,000 for providing fake three-year work experience certificates, the ICAC said. The documents were intended to get trainees admitted to courses organized by training institutions that are recognized by the Labour Department, and acquire the relevant qualifications after completing them. Initial investigations revealed that all the forged certificates were issued by the five engineering companies.

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In the case of the electricians, it’s alleged that an electrical company owner had accepted illicit payments to help inexperienced workers obtain licenses from the EMSD. The owner charged each worker about HK$20,000 in “tuition fees” for a course, and issued bogus documents portraying them as “experienced” electricians.

Initial findings showed that more than half of the work certificates used by the electricians involved were issued by the electrical company owner, while the rest came from four other firms. These companies would list electricity projects for which they were responsible, and falsely claimed that the workers had participated in these projects to deceive the EMSD into granting licenses to these workers.

The EMSD found that some of the licenses had been issued from 2018 to 2021. Some workers had used the licenses to work part time on certain projects, while others had switched jobs.

The suspects detained in this case included the electrical company owner, proprietors of four firms responsible for issuing work certificates, and 32 electricians.

The ICAC said that despite the disparate industries implicated, the perpetrators had adopted a similar fraudulent approach that had greatly put industrial safety at risk.

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The ICAC said it’ll review licensing and registration procedures to strengthen the supervision of professional qualifications in the industry.

About 230 ICAC officers took part in the operation, and all the suspects have been released on bail. The watchdog said investigations are continuing and more arrests are likely.