Internal affairs minister Seiko Noda said Tuesday she will return part of her salary to take responsibility for leaking information she received from another government agency.
"I undermined trust in the government," Noda said. She recently admitted to leaking information to reporters that she had received about a disclosure request filed with the Financial Services Agency on records involving her secretary.
Noda said she will forfeit the roughly 1.6 million yen she has received as a cabinet member since her appointment last August, a punishment she called "a politician's lesson" to herself.
The case could dent Noda's hopes of challenging Prime Minister Shinzo Abe as head of the Liberal Democratic Party in the ruling party's leadership race in September.
"I'm working steadily (to run in the election)," the House of Representatives lawmaker elected for nine consecutive terms said at a press conference.
According to sources close to the matter, the FSA notified internal affairs ministry officials in May that a request had been filed with the agency for the disclosure of records of a meeting involving Noda's secretary in January.
The secretary had accompanied an official from a virtual currency company in the meeting at the FSA. The company had been under investigation by the watchdog for operating without a license.
The FSA had even told the ministry officials that the disclosure request was made by the Asahi Shimbun, one of the country's largest daily newspapers.
Having heard about the information disclosure request, Noda mentioned it in casual conversation with reporters. She later admitted she had acted carelessly.
In a related move on Tuesday, the FSA reprimanded four officials over their involvement in leaking information to internal affairs ministry officials.
Finance Minister Taro Aso admitted the same day that he had confirmed through a probe into the case that the FSA had acted inappropriately in light of the information disclosure law.
Critics say leaks on information disclosure requests risk weakening their role as a check on power.
According to the Ministry of Internal Affairs and Communications, Noda has received 110,000 yen a month for her ministerial role, which together with two bonuses in December and June comes to a total of 1.6 million yen.