China's military has launched joint air and sea patrols around Taiwan in a move described by Beijing as a "stern warning" to separatists against colluding with "foreign elements."

"The patrols and exercises are meant to train the coordination of military vessels and airplanes and their ability to seize control of air and sea spaces," said Shi Yi, spokesperson for the Eastern Theater Command, according to state news agency Xinhua.

Shi said the exercises would test the armed forces' "ability to fight in real combat conditions."

"The patrols and exercises serve as a stern warning to the collusion of 'Taiwan independence' separatists with foreign elements and their provocations," Shi added.

China's ruling Communist Party claims the self-governing, democratic island of Taiwan -- despite never having controlled it. It has vowed to take control of it, by force if necessary.

The patrols come a week after China's foreign minister condemned Taiwan's vice president and presidential candidate William Lai while he was in transit in the US en route to Paraguay -- Taiwan's only diplomatic ally in South America.

China's foreign ministry called Lai a "troublemaker through and through" for his stopover in the US.

The move also comes amid heightened tensions between the United States and China. US President Joe Biden has been hosting the leaders of Japan and South Korea at a trilateral summit undergirded by the three countries' mutual concern over China.

On Tuesday, US-sanctioned defense minister Li Shangfu warned against "playing with fire" when it comes to Taiwan in a veiled jab at the United States when he addressed a security conference in Russia.

While the US has no formal ties with Taiwan, it is one of its strongest international backers in terms of providing the means to defend the island through weapons packages.