More than a third of female workers certified as having mental health issues cited some form of harassment as the main cause, a government survey showed Tuesday.

Some 36.3 percent of women with mental illnesses said that they had suffered from sexual harassment, assault, bullying and abuse of power at work by superiors, according to a survey in a white paper on measures to prevent death from overwork.

About 22 percent of female workers diagnosed with mental disorders said they experienced or observed a traumatic accident or disaster.

The survey also found about 23.1 percent of male workers with mental health issues cited "a change in their job role or workload" as the main cause, while 15.9 percent attributed the problem to assault, bullying and abuse of power.

The survey covered approximately 3,000 people certified as having a mental illness from January 2010 through March 2017, of which women accounted for 31.4 percent.

Among women, those in their 30s comprised the largest group, at 29.5 percent, followed by those in their 20s, at 28.3 percent. Cases involving men were also most numerous among workers in their 30s, at 31 percent, and those in their 40s, at 29.2 percent.

The survey, meanwhile, showed that the number of instances of mental illness and suicide as a result of overwork was the highest among office workers, at 41 cases, followed by salespeople, at 38 cases, and drivers, at 35.

The survey also analyzed working conditions in the construction and media sectors, both notable for their long working hours, between January 2010 and March 2015.

There were 59 cases of mental illness among construction site supervisors. Of those, 30 killed themselves or attempted to do so.

Of suicides among those working in the media, all involved people in their 20s.