A Taiwan court has convicted a former presidential aide of spying for China and three others who were also employed by the ruling Democratic Progressive Party (DPP).

One of the men worked in the office of then Foreign Minister Joseph Wu who now serves as the national security chief.

The court handed the men jail terms of between four to 10 years for leaking state secrets. The ruling stated that the espionage was conducted 'over a very long period of time' and involved sharing 'important diplomatic intelligence.'

Beijing claims democratically-governed Taiwan as its own, and both sides have been involved in mutual spying for decades. However, Taipei asserts that Chinese espionage activities have increased significantly in recent years.

Among the convicted, Huang Chu-jung, a former assistant to a Taipei councillor, received the longest jail time of 10 years. Prosecutors initially sought sentences of up to 18 years.

All four were charged in June, shortly after they were expelled from the DPP. Huang was accused of directing a foreign office staffer to source sensitive information from Wu, subsequently drafting reports based on this intelligence and relaying them to Chinese Communist Party operatives.

The foreign office staffer, Ho Jen-chieh, was sentenced to eight years and two months behind bars.

Huang was also charged with collaborating with former DPP staffer Chiu Shih-yuan, who gathered information from Wu Shangyu, an aide to current President Lai Ching-te.

The court revealed that Huang received nearly NT$5 million ($163,172) from the Chinese government, while Chiu was paid over NT$2 million for their espionage activities.

The court remarked on Thursday that, 'The leaked information involved critical diplomatic intelligence, worsening our country's challenging diplomatic circumstances.'

This conviction is part of Taiwan's broader effort to combat espionage from China, with numerous individuals being prosecuted for similar offenses. Reports in 2024 indicated that 64 individuals were charged with spying for China, marking a stark rise from previous years.

The espionage situation in Taiwan highlights a deeply polarised political climate, with the DPP advocating for a more confrontational stance against Beijing in contrast to the Kuomintang (KMT) party, which favours dialogue.

President Lai has termed China a 'foreign hostile force' while Beijing denounces his administration as a 'destroyer of cross-straits peace,' further complicating the existing tensions in the Taiwan Strait.