Taiwan leader Ma Ying-jeou asked the island's legislative chief to resign on Wednesday because of his alleged involvement in a lobbying scandal.

Wang Jin-pyng, 72, a politician of the ruling Kuomintang, is suspected of lobbying the then-head of Taiwan's justice authority on behalf of a lawmaker from the opposition party, investigators from Taiwan's procuratorial agency announced last week.

Wang is no longer a suitable head of the legislative body, Ma said at an unscheduled news conference on Wednesday morning.

The authority of justice and law will be undermined if the Kuomintang neither expels Wang nor dismisses him from his post as a legislator, said Ma, who is also the party's chairman.

The Kuomintang's disciplinary panel suspended Wang's party membership at a meeting attended by Wang and Ma on Wednesday morning after Ma's news conference, according to Hong Kong-based Phoenix Satellite Television. Wang will be eligible to seek reinstatement to the party in a year.

Earlier this month, Taiwan's procuratorial agency revealed that Wang was suspected of lobbying Tseng Yung-fu, at the time the head of the island's justice authority, in a bid to keep prosecutors from appealing a case involving Ker Chien-ming, a lawmaker from the Democratic Progressive Party, so that Ker's acquittal could stand.

Ma said on Sunday that the scandal marked the most shameful day for Taiwan democracy and justice.

Tseng resigned after the news broke, but insisted he had done nothing wrong. Speaking at a 10-minute news conference on Sept 6, Tseng said he was resigning to avoid undermining the judicial system.

Wang also denied the accusations, saying on Tuesday that he did telephone Tseng and Taiwan's chief prosecutor, but he only reminded them of legislative efforts to curb prosecutors' abuse of their right to appeal acquittals.

The prosecutors abused their power by collecting evidence through wiretapping, and the information should not have been publicized before a verdict, Wang said to his supporters on Tuesday evening.

Wang also said that he is dedicated to the Kuomintang's development, and a partial conviction may jeopardize party unity and undermine the party's government.

Ma said on Wednesday he was disappointed in Wang's statement, and that party unity should be based on integrity, diligence and concern for the people.

Wang is likely to be removed as Taiwan's legislative chief in accordance with Kuomintang rules now that his membership has been revoked, said Chen Xiancai, a researcher at the Taiwan Research Institute at Xiamen University.

Ma and Wang disagreed over some issues related to cross-Straits ties. For example, Ma has been actively pushing the cross-Straits service trade deal, while Wang has used his power to slow down the pace of the deal's passage, Chen said.

The incident will not have a major effect on cross-Straits relations, but the instability of Taiwan politics will hurt cross-Straits communications in the long term, he added.

Xinhua contributed tothis story.

anbaijie@chinadaily.com.cn