Beijing claims the self-ruled island as part of its territory and has threatened to use force to bring it under its control.

The two sides have been spying on each other for decades, but experts say the threat to Taiwan is greater given the risk of a Chinese invasion.

The defendant, identified by his family name Chen, was convicted of violating the Criminal Code of the Armed Forces for passing the documents for a payment of NT$80,000 ($2,700), the court said in a statement.

It did not identify Chen's rank or what kind of information was leaked.

In February 2023, Chen obtained electronic files of military secret-level documents from a classmate under the pretext of "preparing for supervision by his superiors", printed them out and took them out of the camp.

Chen then used his smartphone to photograph the files and sent them to a man he met on the messaging app Line in 2022 when he applied for a loan, the court said.

"He handed over our country's military secrets in exchange for money, which seriously damaged national security," it added.

The court added that Chen received a lenient sentence because he confessed and showed remorse during the investigation and trial.

Local newspaper Liberty Times reported that Chen was a former Marines sergeant addicted to online gaming and owed huge debts.

He can appeal the ruling.