The expulsion of the 32 suspects from Malaysia in April came after another group of Taiwanese fraud suspects were sent to China from Kenya, a move described by Taiwan as "abduction".

The deportations are seen by observers as a means of exerting pressure on self-ruling Taiwan's new president Tsai Ing-wen, who takes office on Friday and has a far more sceptical approach to relations with Beijing than her China-friendly predecessor did.

Taiwan has lodged formal complaints with China over the deportations and has insisted its nationals face investigation and trial on the island.

Beijing says it wants to try the suspects deported from Malaysia on the mainland because they were part of a telecom fraud ring that targeted Chinese victims. China's Ministry of Public Security said they will undergo proceedings under the "mainland judiciary".

"The 32 Taiwanese suspects confessed to committing fraud and have been detained according to law," mainland police said, according to the official Xinhua news agency.

But Taiwan insisted the case was still under investigation.

"Both sides are working together," Chen Wen-chi, who heads cross-strait legal affairs at the Ministry of Justice, told AFP.

Chen, who led a delegation to meet mainland police and discuss the case over the weekend, said the location for the suspects' trial would be "negotiated at a later time".

The Xinhua report quoted a 72-year-old cancer patient who was tricked into depositing two million yuan ($152,835) into a "safety account" as part of the fraud scheme.

"This is my medical savings and it's all been cheated," said the woman surnamed Guo.

"I hope Taiwan will hand these crooks over to the mainland so they can be punished by law," she said.

Twenty other Taiwanese suspects arrested in the Malaysia raids were deported back to Taiwan last month and are currently under investigation.

Chinese state media has also said previously that the Kenya suspects have admitted their guilt and will be tried on the mainland.

Taiwan is self-ruling after splitting with the mainland in 1949, following a civil war, but China still sees it as part of its territory waiting to be reunified.