Labor authorities officially recognized the cases of four Mitsubishi Electric Corp. employees who suffered mental and physical illnesses due to work, two of whom killed themselves, company officials revealed Thursday.

Labor authorities recognized the cases between 2014 and 2017.

The cases include that of a 28-year-old in Nagoya who took his own life in 2012 and an employee in Hyogo Prefecture who died by suicide in 2016.

The other two, one in Hyogo and one at the company’s headquarters in Tokyo, both suffered neurological illnesses.

“We take a serious view of this matter. We have been working to protect the health of our employees by managing their working hours,” the company said in a statement that followed a newspaper report on the cases earlier in the day.

The revelation follows an earlier case in 2016 when a male employee at the Tokyo-based electronics manufacturer was recognized as having become mentally ill due to overwork at its research and development center.

Benefits for employees recognized as having suffered a work-related illness include medical coverage and compensation for leave.

Three of the employees had been working under a discretionary labor system the company introduced in 2004, which only compensates workers for a fixed number of overtime hours rather than the actual hours they may have worked.

It was applied to some 10,000 employees before the company scrapped the system this March.

The company said the move to end the system was unrelated to any of the cases, but was aimed at getting a better understanding of its employees’ working hours so it could reduce them.

A similar discretionary labor system was at the heart of a controversy earlier this year as the administration of Prime Minister Shinzo Abe sought to make more businesses curb their employees’ long working hours. Data the labor ministry provided in support of the system were later found to be faulty.

Opposition parties have argued the system would encourage even longer unpaid working hours.

In June, the Diet passed a labor revision bill that didn’t include the most contentious elements of the discretionary system.

The legislation will set a legal cap on overtime, ensure “equal pay for equal work” for regular and nonregular workers, and exempt skilled professional workers with high wages from working-hour regulations.