Between Sunday and Monday morning, 26 aircraft and 13 warships were operating around the island, while another 13 planes were detected since the early hours of Monday, according to Taiwan's defence ministry.

China's Shandong carrier was also detected Monday around 60 nautical miles southeast of Taiwan's southernmost tip Eluanbi, sailing eastward and entering the Western Pacific for training, the ministry added.

China claims self-ruled Taiwan as its territory and has vowed to take it one day -- by force if necessary.

In recent years, Beijing has ratcheted up military and political pressure on Taiwan, often conducting naval exercises or sending warplanes buzzing overhead to coincide with any diplomatic engagements with Taipei.

Taiwan said 22 of the 39 planes it had recently detected crossed the median line of the Taiwan Strait, a narrow waterway between the island and China.

"The military is closely monitoring the situation and has tasked aircraft, navy vessels, and land-based missile systems to respond," Taiwan's defence ministry said in a statement.

On Saturday, China said its troops were "on constant high alert" after the two ships belonging to the United States and Canada sailed through the Taiwan Strait.

The US Navy said the ships were the Arleigh Burke-class guided-missile destroyer USS Ralph Johnson and HMCS Ottawa, and that the transit ""demonstrates the commitment of the United States and our allies and partners to a free and open Indo-Pacific".

The United States and Western allies have increased "freedom of navigation" crossings of both the Taiwan Strait and the disputed South China Sea to reinforce that both are international waterways, angering Beijing.

In April, Beijing conducted military exercises to simulate the encirclement of the island in April after Tsai met US House Speaker Kevin McCarthy in California.