NHK Chairman Ryoichi Ueda has apologized to the parents of a reporter who died from overwork at the network in 2013, the public broadcaster has said.

On Wednesday, NHK made public for the first time that the death of 31-year-old Miwa Sado was determined by labor standards inspectors in 2014 as having been caused by overwork. Her family had been calling for NHK to make the cause of their daughter's death public.

In a visit to their home Friday, Ueda told the family about the broadcaster's efforts to improve working conditions following Sado's death, according to NHK.

Ueda said at a news conference Thursday that he wanted to meet the parents and speak with them directly.

Covering elections as a reporter in charge of the Tokyo Metropolitan Government, Sado worked 159 hours of overtime with just two days off in a one-month stretch prior to her death.

The case, providing further evidence of severe working conditions many employees endure, comes amid a bid by Prime Minister Shinzo Abe's administration to improve labor practices following the suicide of a new recruit at advertising giant Dentsu Inc. in 2015 due to excessive working hours.