TAIPEI, July 10 (AP) -- Taiwanese prosecutors on Monday indicted the son-in-law of President Chen Shui-bian on insider trading charges, further eroding Chen's leadership position.

Prosecutors indicted Chao Chien-min, the alleged centerpiece in an elaborate insider trading scheme involving a Taipei property company. They say they will demand an eight-year jail sentence.

The move further undermines the position of Chen, who has come under fire recently over a series of high profile corruption cases involving his family and inner circle.

Chen himself has not been implicated in the cases, but Taiwan's opposition has demanded that he step down, saying that the corruption allegations have tarnished his credibility.