Taiwan sent its own forces to monitor, its defence ministry said.
Taiwan's defence ministry said it detected 14 Chinese air force planes operating around Taiwan and carrying out "joint combat readiness patrols" with Chinese warships on Wednesday.
China, which views Taiwan as its own territory, has over the past four years regularly sent warplanes and warships into the skies and waters around the island as it seeks to assert sovereignty claims that the Taipei government rejects.
Taiwan's defence ministry said that starting around 1 p.m. (0500 GMT) on Wednesday it had detected 14 Chinese aircraft including J-16 fighters and drones operating off northern and southwestern Taiwan.
Nine of those aircraft crossed the Taiwan Strait's median line, or areas close by, working with Chinese warships to carry out "joint combat readiness patrols", the ministry added.
There was no immediate response from China's defence ministry. China is in the middle of its week-long Lunar New Year holiday.
Taiwan sent its own forces to monitor, its defence ministry said.
The strait's median line once served as an unofficial barrier between the two sides, but Chinese planes now regularly fly over it. China says it does not recognise the line's existence.
Taiwan last month elected Vice President Lai Ching-te as its next president, a man China describes as a dangerous separatist.
Lai, who takes office in May, has offered talks with China, which have been rejected. He says only Taiwan's people can decide their future.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)