Taiwan says it scrambled fighter jets to track two Chinese military planes that crossed into its airspace at least two times on Monday.
Taiwanese officials said the Yun-8 aircraft left without incident after being warned off by Taiwanese jets.
They said the Chinese transport aircraft took off from China's Guangdong province and were headed in the direction of the South China Sea.
Beijing has not responded to the allegation.
Even though economic and diplomatic ties between China and Taiwan have improved in recent years, tensions persist.
Taiwan split from China following a civil war in 1949. But Beijing still regards it as a breakaway province that will someday be reunified with the mainland.
The reported intrusion into Taiwan's airspace comes days after the U.S. said a Chinese fighter jet came within meters of an American plane off China's coast.
Beijing dismissed U.S. criticism of that incident as "groundless," saying its pilot maintained a safe distance from the American aircraft.
The U.S. Defense Department said the encounter posed a risk to the safety and well-being of the air crew and was inconsistent with customary international law.
In recent months, Japan has also accused Chinese fighter jet pilots of flying too close to Japanese planes in disputed waters in the East China Sea.
