Beijing, which views Taiwan as its own territory to be seized one day, has stepped up military and political pressure on the island in recent years as relations deteriorate.

"68 PLA aircraft and 10 PLAN vessels around Taiwan were detected" between Wednesday and Thursday morning, Taiwan's defence ministry said in a statement, referring to China's army and navy.

The number included figures from Wednesday morning, when Taipei said 35 warplanes were detected around the island.

Taiwan's defence ministry said some of the planes and warships detected on Wednesday were heading to an unspecified area of the Western Pacific to "conduct joint sea and air training with the Shandong aircraft carrier".

The Shandong is one of two operational aircraft carriers in the Chinese fleet.

Taiwan's defence ministry said it detected the Shandong carrier around 60 nautical miles (111 kilometres) southeast of the island's southernmost point heading into the Western Pacific.

The Fujian, Beijing's third and biggest carrier, was launched last year but authorities have not said when it will enter service.

China has not officially commented on any drills being conducted in the Western Pacific.

But the country's Eastern Theatre Command -- which organises drills around Taiwan -- said Wednesday an "aviation unit" had carried out training "recently", in a range of "thousands of kilometres".

It did not mention Taiwan.

- 'High alert' -

Last week, China said its troops were "on constant high alert" after 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, China conducted military exercises to simulate the encirclement of Taiwan after President Tsai Ing-wen met US House Speaker Kevin McCarthy in California.