Lee was speaking at the lectern during an Internal Administration Committee session discussing relations with China when Chiu made loud remarks. Lee accused her of not having been well educated by her parents.

Chiu rose to approach the lectern and spar with Lee, who challenged her to hit him. When Lee faced his fellow lawmakers complaining about her and reportedly using insulting remarks, Chiu approached him from behind and slapped him on the left cheek, cable stations showed.

Lee accused the DPP of being a violent party, leading to a mass of lawmakers from both parties surging to keep their two colleagues apart. The committee meeting was adjourned.

At a news conference after the clashes, Chiu said Lee was the least-qualified lawmaker to insult anybody's family situation because of the problems surrounding his own sister. Diane Lee resigned her legislative seat last January after she was found to have illegally held dual U.S.-Taiwan citizenship since the start of her elected political career in 1994. The DPP said she should pay back her salary from her 14 years as a member of the Taipei City Council and the Legislative Yuan.

DPP chairwoman Tsai Ing-wen later said she supported Chiu against the verbal violence and the majority violence of the KMT.

The KMT demanded the Legislature take disciplinary action against Chiu and the DPP apologize.

Lee accused Chiu and her DPP colleagues of violence, claiming his aide had also been hit. He later went to the Taipei Prosecutors Office to file a complaint. Chiu could not evade responsibility because the whole incident had been registered on tape, Lee said. He said that as a man, he was unwilling to hit a woman, so he had not struck back at Chiu. If she apologized, he was willing to drop the case, he told reporters.

Chiu's father, influential Pingtung County politician Chiu Mao-nan, later told reporters Lee's comments had been irresponsible and "low class."

The DPP said a lack of respect by government officials for the Legislative Yuan was at the source of the incident. The committee meeting was slated to hear an official report on next Sunday's planned cross-straits agreements, but Taiwan's top negotiator, Straits Exchange Foundation Chairman P.K. Chiang, had asked for leave.

Taiwan's Legislative Yuan earned a reputation for frequent massive brawls in the 1990s, but in recent years such incidents have been rare.