NHK, Japan's sole public broadcaster, said Tuesday that Kenji Sobata, senior director for international services, resigned the same day over controversial comments made by an outside staff member in Chinese-language news aired on its international and domestic radio channels.

Four other executives, including president Nobuo Inaba and executive vice president Tatsuhiko Inoue, will return 50% of their salaries voluntarily for a month.

The public broadcaster said those steps are designed to clarify responsibility for the incident, saying that the comments caused an extremely serious situation by violating NHK's standards for international broadcasting that represent the official views of the Japanese government. It also cited faults in advance preparations and in its subsequent response.

"This incident can be described as a takeover of broadcasting. As president, I can't tolerate it," Inaba said at a news conference.

The Chinese outside staff member said in international and domestic Chinese-language radio news on Aug. 19 that the Japanese-administered Senkaku Islands were part of Chinese territory and that Chinese people must not forget the 1937 Nanjing incident, the comfort women issue and Unit 731.

An NHK group company that hired the 48-year-old staff member in 2002 has already terminated its contract with him. The broadcaster filed a lawsuit against him on Monday for damaging its reputation.