Masakuni Murakami, the former Liberal Democratic Party heavyweight at the center of a widening bribery scandal, testified under oath before the Diet on Wednesday but refused to reply to questions that he claimed could incriminate him before his possible indictment by prosecutors.

Masakuni Murakami gives sworn testimony before the Diet.

Appearing before the Upper House Budget Committee as a sworn witness, Murakami refused to elaborate on his ties to the scandal-tainted mutual-aid foundation KSD despite repeated warnings from the committee chairman that his actions could lead to a prison term of up to 12 months.

Murakami, whose resignation from the Upper House was approved by the chamber Monday, maintained throughout the two-hour session that some questions regarding his ties to KSD are best handled by prosecutors.

"This is neither a court nor an investigative authority," Murakami said as he dodged questions from Susumu Yanase, a member of the Democratic Party of Japan. "I have plenty of reasons to refrain from giving testimony."

Speculation is rife that the special investigation department of the Tokyo District Public Prosecutor's Office will summon Murakami for questioning -- and possible arrest -- on charges of bribery once his testimony in the Diet ends.

Murakami was the leader of the LDP's Upper House members until mid-January, and his arrest would add to the intensifying pressure on Prime Minister Yoshiro Mori to resign.

The Mori administration has been battered by a series of blunders and scandals involving Cabinet ministers and LDP lawmakers that have sent his popularity ratings plummeting to record lows.

In a news conference after Murakami's testimony, Takenori Kanzaki, leader of New Komeito, one of the LDP's coalition partners, indicated that he hopes Mori will announce his intention to step down before the LDP holds its party convention on March 13.

"Since I will attend (the event as a guest), I hope I'll be able to experience it with a feeling of refreshment," he told reporters.

In his testimony, Murakami denied claims that KSD was his patron, saying the scandal-hit foundation was just one of his many support groups.

"I would like to prove my innocence through judicial proceedings," Murakami said.

Murakami reportedly received 50 million yen in cash in October 1996 from KSD in return for asking questions in the Diet earlier that year in support of establishing a college the firm advocated -- an allegation Murakami has denied.

In exchange for the alleged political favor, KSD is also believed to have paid for the rent on his office between 1996 and 1998, a cost of some 22 million yen.

Other benefits Murakami allegedly received from KSD include its support and a 620 million yen fund for his 1992 and 1998 Upper House election campaigns.

"I feel awed," Murakami told reporters before entering the session.

Murakami arrived at the nationally televised session with his lawyer and said at the outset that a Feb. 22 phone call from a prosecution investigator asking him to voluntarily submit to questioning as a "suspect" prompted his resignation from the Diet.

"Then, I thought of the honor of a politician. Being under investigation while maintaining my lawmaker status seemed just intolerable to me," he said.

Murakami is the first politician to testify before the Diet since 1997, when Upper House member Tatsuo Tomobe was called to testify under oath over fraud allegations. After the testimony, LDP Secretary General Makoto Koga said the Diet should no longer deal with the suspicions surrounding Murakami's dubious ties with KSD, saying there is a limit to what the legislature can do when the matter is being investigated by prosecutors.

Koga told reporters that he believes Wednesday's testimony put an end to the matter as far as the Diet is concerned, saying that the LDP would not accept the opposition's demand to have Murakami testify again in the Lower House.

However, New Komeito's Kanzaki expressed disappointment that Murakami refused to testify on key matters, adding that the former LDP lawmaker should have discussed the details in public.

Meanwhile, the four major opposition parties -- the Democratic Party of Japan, the Liberal Party, the Social Democratic Party and the Japanese Communist Party -- agreed to immediately submit a no-confidence motion against the Mori as soon as Murakami is arrested.

"Murakami's arrest will make it all the more necessary for the opposition to submit the motion," a senior DPJ official said. "If one of the five (senior LDP members who reportedly handpicked Mori last April) is arrested, we need to lay the blame on the prime minister."