Two-thirds of companies inspected by the labor ministry in fiscal 2016 for suspected labor violations were found to have broken the law either by forcing employees to work illegal overtime or by failing to carry out measures to ensure their health, the ministry announced Wednesday.

The Health, Labor and Welfare Ministry checked the practices of 23,915 businesses suspected of exploiting their employees. The results showed that 10,272 firms, or 43 percent, had workers putting in hours beyond the limit set by individual companies and labor unions. The figure is significantly higher than a year earlier when 5,775 businesses were found in breach of such agreements.

In the report, 7,890 of the 10,272 businesses had employees working for more than 80 hours of overtime a month.

The inspection also found that 1,478 companies did not pay for overtime and 2,355 had not carried out legally mandated measures to ensure workers’ health, such as offering medical checkups and consultations with industrial physicians.

The sizable increase in the number of violations was attributable to tougher crackdowns, according to the ministry.

In previous years, the ministry only targeted companies suspected of having their workers put in 100 hours of overtime a month or more. For fiscal 2016, the ministry expanded the scope of its probe to companies where workers logged 80 hours of overtime or longer — a level that is medically judged as raising the risk of karoshi (death from overwork).

By industry, illegal overtime was most prevalent among manufacturers, followed by transport companies, retailers and wholesalers.

The inspection found that some businesses had workers logging way longer than 100 hours. Of the 10,272 companies, 4,391 firms were found to have workers putting in between 100 to 150 hours of overtime, while 932 companies had workers recording 150 to 200 hours. What’s more, 236 businesses had employees doing more than 200 hours of overtime per month.