TAIPEI, June 18 (Xinhua) -- Taiwan's High Court on Friday ruled that the island's ex-leader Chen Shui-bian will remain in custody for another two months.

It has been the fourth time the court has extended Chen's detention.

Chen is currently preparing an appeal to the Supreme Court against a 20-year jail term for corruption.

On June 11, the High Court upheld Chen's conviction on graft charges but cut his life sentence to 20 years after his appeal.

Chen received a three-month detention order in September last year, and his detention period was extended three times. The previous detention order was due to expire next Wednesday.

He has been in custody for more than 500 days.

Chen, 59, and his wife were both sentenced to life imprisonment by the Taipei District Court in September last year for corruption, embezzlement, money laundering and other abuses when he was in power from 2000 to 2008.

They were found to have embezzled 104 million New Taiwan dollars (3.15 million U.S. dollars) in public funds.

Chen's wife Wu Shu-chen's life conviction for graft was also reduced to 20 years by the High Court on June 11.