Taiwan's defence ministry on Thursday said that China had carried out a "joint combat readiness patrol" near the island for the second time in a week.
Over the past four years, China's military has significantly ramped up its activities around democratically-governed Taiwan. Beijing views the island as its own territory, a position the government in Taipei strongly rejects.
The ministry said that starting from 4 p.m. (0800GMT) on Thursday it had detected 15 Chinese military aircraft, including Su-30 fighters, carrying out "joint combat readiness patrols" with Chinese warships around Taiwan.
Ten of the aircraft crossed the Taiwan Strait's median line, or areas nearby, and flew into air space to the island's north, centre and southwest, the ministry said.
The median line used to serve as an unofficial border between Taiwan and China, but Chinese military aircraft now regularly cross it. China says it does not recognise the line's existence.
China's defence ministry did not answer calls seeking comment on Thursday, the country being in the middle of its Labour Day holiday.
Taiwan reported a similar Chinese combat patrol on Saturday.
The island's top security official said on Wednesday that Taiwan is on alert for China to carry out military exercises following the inauguration of President-elect Lai Ching-te later this month.
Taiwan National Security Bureau Director-General Tsai Ming-yen said China had begun using unusual new tactics, including staging night time combat patrols.
China has a strong dislike of Lai, believing him a dangerous separatist. China's government has rejected his repeated offers of talks, including one made last week.
Lai says only Taiwan's people can decide their future.
