Taiwanese prosecutors on Saturday questioned former president Chen Shui-bian`s wife in a corruption probe, days after the ex-leader was detained in connection with the same case.

The wheelchair-bound Wu Shu-chen was questioned at her home in an upmarket Taipei district instead of the prosecutor`s office due to her frail condition, prosecutors said.

Wu is being questioned on suspicion of graft and forgery over the alleged embezzlement of around 15 million Taiwan dollars (about 450,000 US) during Chen`s term in a case which also implicates the former president.

The ex-leader has admitted submitting falsified expense forms to claim state funds but said the money was used for `secret diplomatic missions,` not for his personal benefit.

Chen has also admitted his wife wired 20 million US dollars abroad from past campaign funds but has denied laundering money.

Chen`s son Chen Chih-chung and daughter-in-law Huang Jui-ching were interrogated on Friday over the alleged transfer of 21 million US dollars to Swiss bank accounts belonging to Huang in 2007. The funds have since been frozen.

The couple have said they were not aware of the source of the funds and were only following the orders of Wu.

The former president`s detention is the latest development in a long-running corruption probe against the former leader.

A court ordered Chen to be locked up Wednesday after 24 hours of high drama during which he was led away in handcuffs, taken to hospital after claiming he had been beaten by police and then finally put behind bars.

Chen, the first former Taiwanese leader to be arrested, could be held for up to four months before prosecutors have to charge him.

The former president, whose pro-independence stance in office set him against Beijing, has repeatedly accused the island`s China-friendly government of being behind the allegations of embezzlement, money laundering, taking bribes and forgery.

Beijing regards Taiwan as part of its territory to be retaken, by force if necessary.