Head of Taiwan's legislative body Wang Jin-pyng speaks to reporters in Taipei September 11, 2013. [Photo/Agencies]

TAIPEI - Taiwan leader Ma Ying-jeou on Wednesday urged Wang Jin-pyng, head of the island's legislative body, to step down after the latter's alleged involvement in a lobbying scandal.

Wang is no longer suitable to head the legislative body, said Ma at a press conference before the island's ruling party of Kuomintang (KMT) held a disciplinary meeting to discuss this issue.

Later Wednesday morning, the KMT disciplinary meeting decided to withdraw Wang's party membership.

If the KMT neither expel Wang nor dismiss him from his post as a legislator, the authority of justice and law will be further undermined, said Ma, also KMT chairman, at the press conference.

Last week, investigators from Taiwan's procuratorial agency revealed that Wang, a seasoned KMT politician, was suspected of lobbying Tseng Yung-fu, then head of the island's justice authority, for prosecutors to not appeal in a case involving Ker Chien-ming, a senior lawmaker of the opposition Democratic Progressive Party, so that Ker could be acquitted.

Tseng resigned after the news broke.

Wang denied the accusations on Tuesday after returning from Malaysia, where he had been organizing his daughter's wedding ceremony.

Despite harsh statements made about Wang's scandal in the past few days, Ma said he had not asked Wang to step down and hoped he could resign himself so as to protect the image of the party.

However, he said he was disappointed about Wang's response on Tuesday and "left with no option but to step forward to face a cardinal issue of right and wrong."

Wang said in his Tuesday statement that he did telephone Tseng and Taiwan's chief prosecutor, but the calls were only made to remind them of legislative body decisions on efforts to curb abuse of prosecutors' powers to appeal.

He also questioned the means of evidence collection as the information was collected through wiretapping.

In his statement, Wang warned that a partial conviction may jeopardize party unity or even cause the party to fall apart, which may eventually lead to the party's loss of governance advantages.

In response to Wang's call for party unity, Ma said this unity should be based on integrity, diligence and care for people.

"As KMT chairman, I have to make a clear stand," he said, calling on all KMT members to take the side of justice and safeguard the KMT's reputation.