The sorties come less than a month before the May 20 inauguration of new Taiwan president Lai Ching-te, who China regards as a dangerous separatist.

"We detected activities from 22 PLA aircraft... since 9:30 am (0130 GMT)," it said in a statement released at 12:10 pm on Saturday.

"12 aircraft crossed the median line and entered Taiwan's northern and central air defence identification zone," it said, adding that the warplanes and drones joined Chinese naval vessels in "joint combat patrol".

The median line bisects the Taiwan Strait, a narrow 180-kilometre (110-mile) waterway separating the island from mainland China.

Beijing, which does not recognise the line, claims democratic Taiwan as part of its territory and has never renounced the use of force to bring the island under its control.

Under the administration of Taiwanese President Tsai Ing-wen, tensions between Beijing and Taipei have ramped up, as she and her government reject China's claim to the island.

Her deputy, Vice President Lai, won the island's January presidential election despite warnings from Beijing that he would cause "war and decline" for Taiwan.

Saturday's show of military might comes as the United States and the Philippines are conducting joint military exercises, including near the potential flashpoints of the South China Sea and the Taiwan Strait.

The joint drills involve a simulation of retaking enemy-occupied islands in areas facing Taiwan.

Beijing claims the South China Sea almost in its entirety despite an international ruling that the claim has no legal basis, and recent clashes between Chinese and Philippine vessels have stoked fears of wider conflict.

China's foreign ministry has accused the United States of "stoking military confrontation".