Beijing has consistently expressed its goal of reunification with Taiwan, using diplomatic, economic, and military pressure to isolate Taiwan internationally.

Taiwanese charged with suspicion of spying on behalf of China rose by a third to 64 people last year, the island's National Security Bureau said, adding most were current or retired soldiers. China has stepped up political and military pressure in recent years to back its claim that democratically governed Taiwan is its own territory.

Taiwan's defence ministry said on Thursday that Chinese warplanes and warships had carried out the first "combat patrol" around the island of the New Year, after Taiwan President Lai Ching-te again expressed willingness to talk to Beijing.