People's Liberation Army Air Force (PLAAF) Chengdu J-10 fighter jets, manufactured by Chengdu Aerospace Corp., a unit of Aviation Industry Corp. of China (AVIC), fly during an aerobatics display during the China International Aviation & Aerospace Exhibition in Zhuhai, Guangdong province, China

A second day of drills by China's military close to Taiwan were aimed at improving combat capabilities, the People's Liberation Army said, after Taiwan's air force scrambled to intercept Chinese jets that briefly crossed the Taiwan Strait's mid-line.

Tensions have spiked between China and the island since Sunday, when Taiwan F-16s shadowed Chinese fighters and bombers which flew around the island.

Beijing claims Taiwan as its territory, to be taken by force if needed.

On Monday, Taiwan's air force scrambled after Chinese jets briefly crossed an unofficial middle line in the Taiwan Strait, which both sides' forces generally stay on their respective sides of.

In a statement late on Monday, the People's Liberation Army Eastern Theatre Command said its forces carried out "air-ground assault and fire support drills to further refine and test their multi-service joint combat capabilities".

China has stepped up such drills since Taiwan President Tsai Ing-wen first took office in 2016, believing she wishes to push for the island's formal independence, a red line for China.

Tsai, who won re-election by a landslide last month on a platform of standing up to China, says Taiwan is an independent country called the Republic of China, its official name.

China's Eastern Theatre Command said that "Taiwan independence forces have ignored national justice and stepped up their pursuit of independence".

"The theatre forces always maintain a high degree of alertness, follow closely the situation and resolutely fulfil their missions," the statement added.

Taiwan has denounced the drills as a threat to regional peace, and says the island will not buckle in the face of China's threats.

Taiwan Premier Su Tseng-chang told reporters on Tuesday that China's military actions had "unnecessary triggered resentment among Taiwanese and harassed regional peace."

"We still hope China could really alleviate people's suffering due to the disease outbreak," Su said. "China should use all the power it has to help its people."

Tsai said on Monday that China should focus on tackling the outbreak of the new coronavirus rather than menacing the island.