Democratic Party of Japan lawmaker Yoshitake Kimata resigned Tuesday from the largest opposition party for assaulting and injuring a woman at a bar in Aichi Prefecture, but he said he will not give up his Diet seat.

After he handed in his resignation, Kimata told reporters at the Diet he decided to leave the DPJ to spare the party any trouble during the current legislative session. He said he will stay in the Upper House as an independent.

The DPJ decided at an executive meeting to accept his resignation.

Kimata pointed out it is a crucial time for the party as the DPJ is grilling the ruling Liberal Democratic Party over serious issues, including mad cow disease, the Livedoor scandal, building-data falsification and bid-ridding involving the Defense Facilities Administration Agency.

He also expressed concern that if he stayed in the party, the incident would negatively affect upcoming elections, including the Upper House race in July 2007.

"I would like to express my deepest regret for having caused a lot of trouble for the victim, the public, my supporters and my beloved DPJ," Kimata said. "In order to clarify my responsibility, I handed in my resignation this morning."

Kimata allegedly assaulted the woman in her 30s in Toyohashi, Aichi Prefecture, on Dec. 29. Police have turned the case over to prosecutors.

Allegations that Kimata had physically abused others, including his secretary, have also cropped up, prompting the DPJ to investigate.

While Kimata continues to deny the allegations, claiming they are the result of "differences in interpretation," DPJ Secretary General Yukio Hatoyama released a statement Tuesday that "unfortunately, the probe could not clear Kimata of the accusations."