China claims self-ruled democratic Taiwan as its territory, and in recent years has ramped up air and sea incursions around the island.

"A (People's Liberation Army Navy) flotilla of 3 ships, led by the Shangdong aircraft carrier, passed through the Taiwan Strait around noon today," the ministry said in a statement, referring to China's navy.

The flotilla went "to the west of the median line, heading northward", it added, referring to the unofficial border in the middle of the strait.

While the presence of Chinese warships is constantly monitored and announced near-daily by Taipei, the passage of the Shandong through the 180-kilometre- (110-mile-) wide Taiwan Strait -- which separates the island from continental Asia -- is unusual.

Taiwan's armed forces "have monitored the situation and tasked (civil air patrol) aircraft, navy vessels, and land-based missile systems to respond to these activities," the ministry said.