Taiwan's high court Monday decided to extend the detention of ex-leader Chen Shui-bian for another three months.

As Chen's family still holds a large amount of illegally-gained property abroad and has not returned it all to the Taiwan authorities, Chen is likely to flee the island, the court verdict said.

Chen has been in custody since December 30, 2008. He was convicted of taking bribes and money laundering and sentenced to life imprisonment at a trial in September last year.

At a second trial in June this year, the high court reduced the penalty to 20 years imprisonment. Both Chen and prosecutors appealed the decision.

On Monday, the case was handed to the Taiwan's "Supreme Court" for the third and final trial.

Chen's wife Wu Shu-chen was also sentenced to life imprisonment at the first trial, which was reduced to 20 years at the second trial.

According to the court, Chen's family had $22.43 million in illegally-gained property in Switzerland but has returned just 11.52 million of it to Taiwan authorities.