Eight Chinese aircraft crossed the median line of the Taiwan Strait on Tuesday morning, Taiwan's defence ministry said, as China ramps up military pressure on the democratic island.

Taiwan, which China claims as its own territory despite the island's strong objections, has faced in recent years almost daily missions by Chinese military aircraft, often in the southwestern part of the island's air defence identification zone.

A total of 24 Chinese warplanes, including fighter jets and bombers, were spotted near Taiwan on Tuesday morning starting at about 8 a.m. (0000 GMT), the defence ministry said, adding four Chinese warships also joined a "joint combat readiness patrol".

Taiwan sent aircraft and ships to warn away the Chinese, while missile systems monitored them, the ministry said, using standard wording for its response.

In a statement, the ministry said it is the joint responsibility for all parties in the region to maintain safety and stability.

"Any provocative behaviour that could bring impacts is not good for regional safety," it said.

China, which has never renounced the use of force to bring Taiwan under its control, in April staged drills around the island in anger at President Tsai Ing-wen's meeting with the speaker of the U.S. House of Representatives.

Taiwan's government strongly objects to China's sovereignty claims and vows to defend itself if China attacks the island.