Taipei's coast guard warned off Chinese vessels.
Beijing commenced two days of war games, dubbed «Joint Sword-2024A», as a «strong punishment» for Taiwan's «separatist acts».
They come after the island swore in President Lai Ching-te, who said in his inaugural speech on Monday that Taiwan «must demonstrate our resolution to defend our nation».
China — which claims Taiwan as part of its territory — has denounced Lai's speech as a «confession of independence».
Beijing's drills began Thursday morning and are taking place in the Taiwan Strait and to the north, south and east of the island, China's People's Liberation Army (PLA) said.
In response, Taiwan's armed forces dispatched «aerial, naval and land assets», Taipei's defence ministry said in a statement.
Four fighter jets took off at around 1:00 pm (0500 GMT) from a military airbase in Hsinchu, an hour southwest of Taipei.
Taipei's ministry of defence said around 8:00 pm (1200 GMT) it had detected 49 Chinese fighter jets and air patrol planes around Taiwan since 7:20 am — the highest number of Chinese aircraft observed around the island in a single day so far this year.
The defence ministry said earlier in the day it had detected 15 Chinese warships and 16 coast guard vessels.
The closest they got to Taiwan was about 24 nautical miles (44 kilometres), said senior intelligence official Huang Wen-chi, adding that the military has «not detected any use of live ammunition».
Ministry spokesman Sun Li-fang said China's exercises were «destructive» to regional