BEIJING, Jan. 28 (CNA) - China toughened its language towards Taiwan on Thursday (Jan 28), warning after recent stepped up military activities near the island that "independence means war" and that their armed forces were taking action to respond to provocation and foreign interference.

Taiwan, claimed by China as its own territory, reported multiple Chinese fighter jets and bombers entering Taiwan's southwestern air defence identification zone over the weekend, prompting concern in Washington.

China believes that Taiwan's democratically-elected government is moving the island towards a declaration of formal independence, though President Tsai Ing-wen has repeatedly said they are already an independent country called the Republic of China, its formal name.

Asked at a monthly news briefing about the air forces' recent activities, Chinese Defence Ministry spokesman Wu Qian said Taiwan was an inseparable part of China.

"The military activities carried out by the Chinese People's Liberation Army in the Taiwan Strait are necessary actions to address the current security situation in the Taiwan Strait and to safeguard national sovereignty and security," he said.

"They are a solemn response to external interference and provocations by 'Taiwan independence' forces," he added.

The Chinese incursions coincided with a US carrier battle group entering the disputed South China Sea to promote "freedom of the seas".

Wu said a "handful" of people in Taiwan were seeking the island's independence.

"We warn those 'Taiwan independence' elements: Those who play with fire will burn themselves, and 'Taiwan independence' means war," he added.