The arrest of a Taiwanese general accused of spying for China is a warning to Taiwan to be wary of its old foe despite warming economic links that are likely to stay unscathed by the case.

The 51-year-old officer, Major-General Lo Hsien-che, is accused of collecting intelligence for Beijing for at least six years and is believed to be the highest-ranking Taiwanese military official accused of espionage for China.

The arrest has underscored the persistent distrust and military tension between Taipei and Beijing, despite the signing of landmark trade and tourism deals after Ma Ying-jeou was elected as Taiwan's president in 2008 and embarked on an effort to narrow the rift with China.

Though the warmth of spring has come to the situation between both sides of the Strait, beneath the surface the undercurrents are as choppy as ever, Taiwan's United Daily News wrote on Thursday.

National security authorities must draw lessons from this bitter experience and make sure it does not happen again.

Taiwan's government says Lo was recruited in 2004 while he was posted to Thailand.

Taiwan's freewheeling media, which never shies away from a scandal, has voiced surprise that such an apparently low-key man as Lo could have been a spy.

Lo was fond of health and fitness books, never demanded military underlings run errands for him and came from a military family, Taiwan's China Times reported.

He loved his posting to Thailand, so much so that he earned the nick-name Thai Lo, and had good contacts with the Thai military, the newspaper added.

The impression he gave was of being sincere and honest. He didn't say much, was very introverted and low key, it quoted a military source as saying.

The United Daily News said Lo had betrayed Taiwan because of women and money, providing China with detailed information about Taiwan's military communications network via a female Chinese spy who masqueraded as a well-travelled trader.

A spokeswoman for China's Taiwan Affairs Office told Reuters by telephone that they didn't understand the details of this case, and declined further comment.

China calls the democratic island an illegitimate breakaway province that must reunify with the mainland, and has never renounced the use of force to achieve that.

Frankly, these types of cases are rather common, and won't have a major impact on cross-Strait relations, said Zhu Feng, a professor of international studies at Peking University in Beijing.

This is just one instance of spy activity. It is not likely to have a major influence on a White House decision on arms sales to Taiwan and won't be an impediment for the Pentagon, Zhu said.

China was furious when the United States decided to proceed with weapons sales to Taiwan last year, but Washington says it is legally obliged to help the island defend itself.

Chinese state media have remained largely mute about the arrest, with the blaring exception of the Global Times, a popular tabloid run by Communist Party mouthpiece, the People's Daily.

The Global Times splashed the news on its front page on Thursday, saying Taiwan was hyping up the story.

Espionage activities have never ceased, even though cross-Strait tensions have eased over the year, it quoted Li Fei, a Taiwan expert at China's Xiamen University, as saying. But these cases won't affect the overall prospects of ties.