A record 5,160 business facilities employing foreign technical intern trainees were told in 2018 to correct practices that violated labor-related laws, the labor ministry has said.

The number shot up from 4,226 in 2017, in line with an increase in foreigners working under the country’s Technical Intern Training Program and companies accepting them, according to the ministry’s announcement Thursday.

Of the total, 23.3 percent were told to correct their practices over illegal overtime work, followed by 22.8 percent that infringed safety standards and 14.8 percent that failed to pay additional wages for overtime and work outside regular daytime hours.

A total of 19 serious cases were reported, for which papers were sent to public prosecutors. In some of the cases, workers were not paid for over six months, and in others the interns worked 180 hours of overtime per month.

Law violations were found at 1,937 business facilities in the machinery and metal industry, the largest number by industry.

The number stood at 936 in the food industry, 502 in the textile and clothing industry, and 474 in the construction industry.

Many foreign trainees are now employed in these industries.