Taiwan's air force had to warn away 27 Chinese aircraft again that had entered its air defense zone on Sunday, Taiwan's defense ministry said, the latest increase in tensions across the sensitive Taiwan Strait.

Chinese-claimed Taiwan has complained for a year or more of repeated missions by China's air force near the democratically governed island, often in the southwestern part of its air defense identification zone, or ADIZ, close to the Taiwan-controlled Pratas Islands.

Over a four-day period beginning on Oct. 1, when China marked its national day, Taiwan said that nearly 150 PLA military aircraft entered its ADIZ, not territorial air space but a broader area Taiwan monitors and patrols that acts to give it more time to respond to any threats.

The latest Chinese mission included 18 fighters jets plus five nuclear-capable H-6 bombers, as well as, unusually, a Y-20 aerial refueling aircraft, the Taiwan ministry said.

The bombers and six of the fighters flew to the south of Taiwan into the Bashi Channel which separates the island from the Philippines, then out into the Pacific before heading back to China, according to a map the ministry provided.

Those aircraft were accompanied by the refueling aircraft, suggesting China refueled the shorter-ranged fighters inflight, a skill that the country's air force is still working to hone to enable it to project power further from China's shores.

Taiwan sent combat aircraft to warn away the Chinese aircraft, while missile systems were deployed to monitor them, the ministry said.

There was no immediate comment from China, which has in the past said such moves were drills aimed at protecting the country's sovereignty.