TAIPEI (AFP) – Taiwan's High Court ruled on Friday that former president Chen Shui-bian should be held in custody for another two months while he appeals a 20-year jail term for graft.

"Chen is highly likely to flee to escape punishment... and he cannot prove that his family no longer has any assets overseas," it said in a statement.

In a surprise move, the court in June cut Chen's life sentence to 20 years in jail after concluding that he had embezzled less money than previously assumed.

Chen, who has been locked up for more than 600 days, has repeatedly vowed that he would not flee the island if set free while his appeal is heard.

The ex-leader was convicted last year at the Taipei district court of embezzling state funds, laundering money, accepting bribes and committing forgery.

The opposition Democratic Progressive Party, which Chen once led, has urged the government to free him immediately.

Chen has blasted his trial as a vendetta carried out by the Beijing-friendly Kuomintang administration in retaliation for his pro-independence stance during his 2000-2008 term.