The opposition leader said that it was "heartbreaking" to be indicted, but that he would "turn indignation and sadness into strength."

"The honesty and integrity I have safeguarded all my life have been doubted. It is more painful than losing my life," Ma said.

"I'll run in the 2008 presidential election to prove my innocence to the nation," Ma announced shortly after he was indicted. "I'll use action to show that voters will choose the side of justice."

Ma was indicted on corruption for transferring mayoral expenses to his salary account during his stint as Taipei's mayor between 1998 and 2006.

Prosecutor Hou Kuan-jen charged that the remittance constituted an act of corruption, which resulted in over NT$10 million in undue gains for the former mayor.

But Ma insisted he respected the rule of law and stressed that he could never accept the embezzlement accusation.

Claiming that hundreds of other government officials had similar problems with their special expenses, Ma said he would fight his case till the end, not just for himself, but also for all the other officials.

He said he treasured his integrity so much that being indicted was more painful than losing his life.

"In the face of the ruling party's unscrupulous persecution, I fear nothing... I will not be knocked down," Ma said.

He also resigned from the KMT chairmanship, as he had promised to step down if indicted.

The KMT's anti-corruption rules would bar him from running in the upcoming primary for next year's presidential race because of the corruption indictment.

Some of Ma's supporters inside the party are trying to change the rules to facilitate Ma's candidacy.

But former KMT Chairman Lien Chan has been said to be against the attempt. Instead, Lien reportedly has suggested that Ma serve as Legislative Speaker Wang Jin-pyng's running mate in the 2008 presidential poll.

The speaker yesterday declined to comment on the possibility of a Wang-Ma ticket.

But he said any unreasonable parts of the KMT's anti-corruption rules should be revised.

KMT Taipei Mayor Hau Lung-bin voiced full support for Ma's presidential bid. But the KMT's ally, the People First Party, did not commit itself to backing Ma. PFP spokesman Lee Hong-chun said his party would only support a presidential candidate agreed upon by both parties.

The ruling Democratic Progressive Party (DPP) meanwhile made fun of Ma's presidential bid.

Ker Chien-ming, head of the DPP's legislative caucus, said an arrested "thief" had now vowed to become a "policeman."

Independent Legislator Lee Ao, a fierce critic of the DPP government, urged Ma to retire from politics, but expressed support for Wang's presidential bid.