TAIPEI (AFP) - A Taiwanese court has sentenced a former intelligence officer to 18 years in prison for reportedly working as a double agent and spying for China as relations worsen with Beijing.

Major Wang Tsung-wu was sentenced Thursday (Sep 22) by Taiwan's High Court on convictions of engaging in espionage as well as violating national intelligence and security laws.

The court provided no further details, citing national security restrictions.

Local media reported how Wang was allegedly turned by China when he was sent there as an undercover agent for Taiwan's Military Intelligence Bureau around 20 years ago.

He spied for Beijing for more than a decade, reports said.

Wang was recruited by China in 1995 and leaked confidential information before he retired in 2005. He also recruited retired colonel Lin Han in 2013 to help collect intelligence, according to Hong Kong-based Apple Daily.

Lin had travelled to Singapore and Malaysia to meet with Chinese intelligence and passed on information about the identities of the Taiwan bureau's officers and their missions, Taipei-based Liberty Times reported.

Wang was paid around US$96,000 while Lin received about US$76,000 for the information they passed, it added.

Lin received a six-year jail term for violating national intelligence law, the High Court said.

Both men can appeal the ruling.

It is the latest in a string of espionage cases and comes as ties between Taiwan and China turn increasingly frosty since Beijing-sceptic President Tsai Ing-wen took office in May.

Taiwan and China have spied on each other ever since they split in 1949 at the end of a civil war. Beijing still regards the self-ruled island as part of its territory awaiting reunification, by force if necessary.

In 2011, an army general who headed an intelligence unit was sentenced to life for spying for China, in one of Taiwan's worst espionage scandals.

That sentence came despite a rapprochement between Taiwan and China under then-president Ma Ying-jeou of the Beijing-friendly Kuomintang party.

Earlier this year a mainland Chinese man was jailed for four years for recruiting a former major-general and other local military officers to spy for Beijing.

The major-general received a sentence of two years and 10 months.