Ruling Liberal Democratic Party Secretary General Taku Yamasaki on Wednesday filed a criminal complaint and a lawsuit against a magazine publisher over a report that he had an extramarital affair, according to his office.

Yamasaki filed the complaint with the Metropolitan Police Department for alleged defamation and the suit at the Tokyo District Court demanding that Bungeishunju Ltd., publisher of the weekly magazine Shukan Bunshun, pay 50 million yen in compensation.

"The report considerably hurt the personality, honor and political credibility of Taku Yamasaki," the office said in a statement. "Thorough investigations and a trial will make that clear."

The magazine's editor, Seigo Kimata, refused to back down, saying the magazine has sufficient evidence, including a tape recording of a conversation between Yamasaki and his alleged girlfriend.

In its latest edition, which went on sale Wednesday, Shukan Bunshun says the woman admitted to having a decade-long relationship with the 65-year-old lawmaker.

The magazine previously ran a series of stories claiming Yamasaki also had an affair with a 29-year-old woman linked to the Unification Church.

Yamasaki told reporters: "I am surprised and outraged. I will make the facts clear during trial procedures."

He said he would take similar action Thursday against the publisher over the stories involving the 29-year-old woman.