A Taiwanese general has been detained on suspicion of spying for China - the highest-ranking officer involved in alleged espionage in decades.
Maj Gen Lo Hsieh-che was recruited by China in 2004 while he was stationed overseas, the defence ministry said.
But officials declined to comment on reports that he had worked in the US and had sold secrets about military communications networks.
His arrest follows an investigation launched last year.
Mr Lo returned to Taiwan in 2006 and was made a major general in 2008, defence ministry spokesman Yu Sy-tue said.
At the time of his arrest, he was head of the military command's communications and information office, Mr Yu said.
The defence ministry has set up a group in an attempt to limit any possible damage, Lt Gen Wang Ming-wo, of the ministry's Political Warfare Bureau was quoted by AFP as saying.
"He has brought shame to the military. Servicemen are supposed to be loyal to their country," Mr Wang said.
'Smokeless war'
Gen Lo is the most senior officer accused of espionage since the 1960s when a vice defence minister was arrested amid a crackdown on Communist spies.
Critics say his alleged connection with China and the fact it took several years to detect has revealed a security loophole.
Tensions have run high between the two sides since 1949, when Taiwan was separated from China at the end of a civil war.
China sees Taiwan as part of its territory and has threatened to use force if the island ever moved to declare formal independence.
But there has been an unprecedented warming in relations since Taiwan's President Ma Ying-jeou took office in 2008.
Despite this, Taiwan's military has repeatedly said that it will not let its guard down against the mainland's government.
"Although tensions across the Taiwan Strait have eased over the past more than two years, the Chinese communists have not stopped their infiltration into Taiwan," said Mr Wang.
"Instead, they have been stepping up their intelligence gathering, what we call the 'smokeless war' against us," he said.
