UNITED NATIONS — A top U.N. executive in charge of informing the public about the world body’s good works is facing a lawsuit in Japan and questions about financial matters in his department’s Tokyo office.

Kiyotaka Akasaka, the U.N. undersecretary-general for public information, is accused of libel in a suit filed yesterday in a Tokyo district court. The suit, brought by a former director of the Department of Public Information’s Japan office, Charmine Koda, stems from internal fighting within the small office.

Ms. Koda, who is seeking $90,000, resigned in June. She says she was punished after complaining about what she said were financial rules violations. “They wanted to drive out someone who would address the issues, and sweep it under the rug instead,” she told The New York Sun last week.

Once a TV anchorwoman in Japan, which is the second-largest contributor to the U.N. budget, Ms. Koda said she was an outsider at the United Nations. She described the organization as a place where longtime employees are resistant to change and where no serious investigations of wrongdoing take place.

Ms. Koda’s problems began soon after she joined the office in April 2006, she said. An audit by the U.N. Office of Internal Oversight Services, initiated after she lodged a complaint, found “major control weaknesses in the management of human resources, procurement and finances” at the Tokyo office. The audit details cases of “fictitious invoices” and advance payments for goods prior to delivery, in violation of U.N. procurement rules. In 2005, according to the audit, such rules violations involved $26,000 of the office’s annual operating budget of $100,000.

In a June article in the Japanese magazine Bungeishunju, Ms. Koda told her side of the story. Despite her resignation, she writes, “I am still a believer” in the United Nations, though she pledges to “fight all the way” to change the system.

Mr. Akasaka responded to the magazine article with a Tokyo press conference. Ms. Koda’s resignation was an “irresponsible” act, Mr. Akasaka told reporters, saying she “injured the honor and dignity of the United Nations.”

Mr. Akasaka’s allegations “are all untrue and seriously injured my honor and reputation,” Ms. Koda told the Sun in an e-mail yesterday. She asked for a retraction and an apology, she said, but Mr. Akasaka failed to respond, so she decided to file the lawsuit. Mr. Akasaka declined to comment on how he would answer the charges in his homeland, saying he had not seen the court papers.

A U.N. official familiar with the case said yesterday that after six of the seven staffers in the Tokyo office lodged complaints against Ms. Koda, Mr. Akasaka attempted to mediate the dispute. But after the publication of the magazine article, Mr. Akasaka had no choice but to defend the integrity of his office, the official said, speaking on the condition of anonymity.

The official added that the financial practices cited in the oversight report ceased immediately after they were exposed.