Taiwan's top court has rejected an appeal by an ex-general sentenced to life in prison for spying for China, the toughest punishment meted out in an espionage case in decades, officials said Friday.

The supreme court made the final decision Thursday on the case of former major general Lo Hsien-che, who is also the highest-ranking official ever to be convicted of spying in Taiwan, defence officials said.

Lo, who was born in 1959, reportedly started working for China in 2004 and was suspected of handing over information relating to a project that gave the Taiwanese military some access to US intelligence systems.

According to Taiwanese media reports, he fell for a honey trap set by a female Chinese agent while stationed in Thailand and received about $1 million from China for his services.

The defence ministry did not specify what type of intelligence Lo gathered for Beijing or how much money he pocketed.

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 island as part of its territory awaiting reunification, by force if necessary.

Since 2008, when Ma Ying-jeou became Taiwan's president on a Beijing-friendly platform, the two sides have seen significant progress. He was reelected in January for a final four-year term.

But Ma has said Taiwan should strengthen its defences against Chinese espionage following a string of spy scandals showing intelligence gathering has continued despite warming ties.