Taiwan's President Chen Shui-bian has rejected corruption allegations against him and refused to step down despite mounting pressure.
President Chen said he "had nothing to hide"
"The charges are unacceptable," Mr Chen said, as thousands of people rallied in Taipei to demand his resignation.
On Friday, prosecutors said they had enough evidence to charge Mr Chen with corruption - although he is protected by presidential immunity.
His wife and three ex-aides were charged with the misuse of state funds.
"I must ask everyone, could A-Bian be this kind of crooked fellow?" Mr Chen said in a long-awaited TV address, referring to himself by his nickname.
"The indictment is nothing but a death sentence to politicians."
Mr Chen said he "decided to face the prosecutors' questioning and investigation because I had nothing to hide" and that he was "willing to resign if the judge convicts me of corruption".
He said he had no motive for corruption and pointed out that he had voluntarily halved his own presidential salary - funds which were far larger than the amount of money allegedly misused from the special allowance fund.
However, Mr Chen added: "I apologise to all our people and the ruling party members for hurting the nation's image and causing political turmoil."
The TV address is being regarded as one of the most important speeches in President Chen's political career, the BBC's Caroline Gluck in Taipei says.
But while Mr Chen rebutted the allegations, he gave no details about the destination of unaccounted funds, our correspondent says.
The main opposition parties have said that if the president does not resign, they will launch a third attempt in parliament next week to force him out of office.
Members of the small Taiwan Solidarity Union political party, a former ally of the president's Democratic Progressive Party or DPP, have said that if the motion is tabled, they would vote along with the opposition.
Many DPP members have argued that President Chen has become too much of a liability and should be replaced before the 2008 presidential elections.
The charges relate to the handling of a secret presidential fund used for diplomatic work overseas. Officials say about $500,000 could not be properly accounted for.
During the four-month investigation, officials looked at six separate cases involving the use of the fund. They said the president's explanation for two were verified, but three were questionable and one was described as pure fiction.
March 2004: President Chen narrowly wins re-election
May 2006: President's son-in-law held over insider trading claims. Charged in July
Allegations of improper conduct involving Chen's wife and senior aides also surface
June: Chen cedes some powers to PM amid outcry
Unprecedented opposition motion to oust him, which fails
September: Two weeks of pro and anti-Chen marches
Opposition launch new bid to recall Chen. Again fails
October: Wu Shu-chen cleared of accepting shop vouchers in return for influence
November: Wu Shu-chen charged with corruption over handling of secret presidential funds
Prosecutors say enough evidence to indict Chen, but he is protected by presidential immunity
After charging the first lady Wu Shu-chen - who has previously denied any wrongdoing - the prosecutor's office said "evidence also showed Chen is suspected of graft and forgery".
"But since he is protected by constitution against criminal charges, he can only be prosecuted after he leaves office," Chang Wen-cheng, of the prosecutor's office, said.
President Chen has been facing growing calls for his resignation in recent months over the scandals to hit his family and office.
Last month, Wu Shu-chen was cleared of accepting vouchers from a department store in return for her influence.
In May, her son-in-law, Chao Chien-ming, was arrested and later charged with insider trading.
Mr Chen, whose term of office is due to run until 2008, ceded some powers to Prime Minister Su Tseng-chang in June to placate his critics.