A Taiwanese air force captain at a radar command and control centre has been arrested for allegedly leaking classified data to China, officials and media said Wednesday.

The captain, identified only by his surname Chiang, was arrested in January for allegedly leaking illegally obtained data to China via his uncle, a Taiwanese businessman based on the mainland, according to a report by the widely-circulated Next Magazine.

It said the Chinese military has long sought access to the centre which houses highly sensitive information including details on the air force's "Strong Net" radar system and the US-made Patriot surface-to-air missiles.

Taiwan's defence ministry spokesman David Lo confirmed the arrest but declined to provide further details on the case while the investigation continues.

But Chen Chen-hsiang, a former general who is now a legislator in the ruling Kuomintang party, said he was "shocked" at the news.

"The unit is supposed to be highly confidential," he said.

Next Magazine cited a military source warning: "Should the air force captain leak electronic factors of the various radar systems to China, the damages from the case would go beyond imagination".

It said the centre in the north is responsible for surveillance of the skies stretching from the island's north to southeastern Chinese coastal provinces like Fujian, Zhejiang and Jiangxi.

Pan Meng-an, a lawmaker from the major opposition Democratic Progressive Party (DPP), called on President Ma Ying-jeou to immediately hold a national security meeting.

Ties between Taipei and Beijing have improved markedly since Ma of the China-friendly Kuomintang party came to power in 2008 on a platform of beefing up trade links and allowing more Chinese tourists to visit.

But the episode has highlighted Beijing's lingering hostilities towards the island, which it still regards as part of its territory awaiting to be reunified -- by force if necessary.

The island has governed itself for more than six decades since splitting from the mainland in 1949 at the end of a civil war.

"On the surface, tensions across the Taiwan Strait have eased. But in reality, they have not," legislator Chen said.

In July last year, a Taiwanese general lured by a honey trap into spying for China was sentenced to life in prison by a military high court, in one of the island's worst spying cases for half a century.

Major general Lo Hsien-che, former chief of the army telecommunications and electronic information department, was indicted in May for spying and taking bribes from China beginning in 2004.

He is one of the highest-ranking Taiwanese to be convicted of spying for Beijing.