TAIPEI - TAIWAN'S former president Chen Shui-bian remained behind bars on Thursday in a corruption probe after a court found an appeal against his detention invalid.

The High Court said in a statement that it has granted three days for Chen's lawyer to validate the appeal by ensuring that the ex-president's signature or finger prints are on it.

However, Chen refused to sign the appeal to protest what he says are politically-motivated allegations against him, said his lawyer Cheng Wen-long, adding that he is planning to bring the case to the island's grand justices.

The detention 'is a violation of the constitution and human rights.

Prosecutors already questioned his wife and son so he could not collude with them,' Mr Cheng told reporters.

Chen's lawyer submitted the appeal despite the ex-president's refusal as he felt such action was in his client's best interests.

Chen was hospitalised earlier this week for dehydration, days after going on hunger strike to protest his detention. He was released from hospital and sent back to the detention centre on Wednesday.

The pro-independence Chen has repeatedly accused the island's China-friendly government of being behind the allegations of embezzlement, money laundering, taking bribes and forgery that also implicate his family.

He is the first former Taiwanese leader to be arrested, and could be held for up to four months before prosecutors have to charge him. -- AFP