Taiwanese authorities said this week that Beijing was holding its biggest maritime drills in years, deploying dozens of warships and coast guard vessels in an area stretching from near the southern islands of Japan to the South China Sea.

Hsieh Ching-chin, deputy director general of Taiwan's coast guard, said Friday that the ships had returned to China, adding that Taipei considered the manoeuvres to be "over".

Asked about the alleged drills on Friday, Wu Qian, a spokesman for Beijing's defence ministry, did not confirm whether they had taken place.

But he said that "whether or not we hold exercises, and when we hold them, are decided by us alone, based on our own needs and the circumstances of our struggle", according to an official social media account of the armed forces.

"Safeguarding national sovereignty and territorial integrity, the fundamental interests of the Chinese nation, and the common interests of compatriots across the Taiwan Strait are the (military's) sacred duties," Wu said.

"No matter whether it holds exercises, the People's Liberation Army will not be absent or soft-hearted when it comes to striking down (Taiwanese) 'independence' and pushing for unification," he said, referring to the Chinese armed forces.

Any effort by Taipei to achieve independence "will inevitably be strictly punished and are doomed to failure", Wu said.

China claims Taiwan as part of its territory and has not ruled out the use of force to bring the self-ruled island under its control.

Beijing has reacted angrily to Taiwanese President Lai Ching-te's recent visit to the United States and call with Republican House Speaker Mike Johnson.