TAIPEI - The wife of Taiwan's embattled leader Chen Shui-bian has gone on trial accused of corruption and forgery in a landmark case that could end his leadership.

Chen has promised to resign if his wife Wu Shu-chen is found guilty by the court in Taipei of illegally claiming 14.8 million Taiwan dollars (US$450,000) in personal expenses from government funds.

Prosecutors indicted wheelchair-bound Wu, 54, and three aides last month, but Chen escaped immediate prosecution because of his immunity.

The corruption charge carries a minimum seven-year prison term and forgery at least one year.

Chen has denied any wrongdoing and said the embezzlement allegations were unacceptable.

Wu, the first wife of a Taiwanese leader ever to be prosecuted and in poor health, showed up at the tightly-guarded courthouse in front of a large crowd of reporters and cameramen.

Her indictment sent political shockwaves throughout the island and prompted the ruling Democratic Progressive Party (DPP) to suspend her membership for 18 months.

Chen's DPP filed a petition Thursday with the Council of Grand Justice in a last-ditch bid to stop the trial going ahead, but it usually takes months for the body to make a decision.