Three witnesses appeared in court to testify: Tseng Tien-tsu, one of Chen's close aides; Li Bijun, in charge of the Taiwan Shinlin Sinseng Pharmaceutical Co. Ltd and involved with Chen's wife's alleged embezzlement and forgery of documents; and James Huang, director of the island's foreign affairs department.

Taiwan businessman Kung Chin-yuan, a witness, asked for leave from the trial, according to media reports.

Friday's session put the focus of the trial of Ma Yung-cheng and Lin Teh-shun, two of Chen's close aides, who allegedly used a part of the secret fund in "secret diplomacy" that was aimed at winning "international cooperation" for Chen's government.

Chen's wife Wu Shu-chen yet again asked for leave from her trial on charges of graft. Wu has missed all the hearings since fainting in court last December.

The prosecutors last November found evidence to indict Chen on charges of graft and forgery of documents in connection with the secret fund, but as Taiwan leader he is immune from criminal charges and a formal indictment against him will have to await the end of his term in 2008.

Wu Shu-chen was accused of embezzlement and forgery of documents involving more than 14.8 million New Taiwan dollars (about 450,000 U.S. dollars).

Chen's other aides were charged with corruption, forgery and perjury.