The defections of Lee Wen-chung and Lin Cho-shui are the first major cracks to appear in the DPP since a prosecutor indicted Chen's wife on November 3 for embezzling money from a special "diplomatic fund" and said that Chen himself could be indicted when his immunity from prosecution lapses after he leaves office.

Chen faces a recall motion in Taiwan's "legislature" on November 24. At least 20 DPP members will have to side with the opposition for the recall to be put to an island-wide referendum for final approval.

In a joint statement, Lee and Lin said they did not support the recall motion because it could create serious rifts in society.

However, they said, they were leaving the "legislature" to express their dissatisfaction over the fund scandal and other alleged corruption cases that have embroiled Chen and his inner circle for the past six months.

"Our party has had a glorious history, but it has also made mistakes," they said. "We're using this small action to make our apology to the public."

The comment appeared to be aimed directly at Chen, who has said he and his wife are innocent of corruption and insisted he will complete the remaining 18 months of his term.

Last week the DPP voted in a closed session to oppose the recall motion, a move that Lee and Lin attacked in their statement.

"Our party (leaders) had promised before that once the 'president' was found to be involved in corruption, he should resign," they said. "But our handling of the matter has failed to meet public expectations. We should have kept our commitments."

The statement by Lin and Lee follows the publication of an open letter on Friday by a former Chen adviser calling on Chen to resign over the corruption allegations.

In the letter Nobel laureate Lee Yuan-tseh urged Chen to "admit mistakes" and choose the "correct option" in dealing with the charges against him.

In another political development, Taiwan prosecutors will question the top opposition party leader and possible 2008 "presidential" candidate today over reports that he misused a special fund, officials said.

The questioning comes 10 days after prosecutors said Chen could have been charged in a case involving embezzlement and forgery if he were not president.

The latest reports involve Ma Ying-jeou, chairman of the opposition Kuomintang (KMT), who is also mayor of Taipei.

The city's Department of Information said yesterday that Ma was innocent and an auditor had already found that he did nothing wrong.

"Lawmakers" from Chen's ruling DPP have accused Ma of illegally diverting funds, local press reports have said.