Taiwan is on alert for China to carry out military exercises after the inauguration of President-elect Lai Ching-te this month, the island's top security official said on Wednesday, adding China has already begun using unusual new tactics.

China, which views democratically governed Taiwan as its own territory, has a strong dislike of Lai, believing him a dangerous separatist. China's government has rejected his repeated offers of talks, including one made last week.

Lai, like current President Tsai Ing-wen, rejects Beijing's sovereignty claims; both say only the island's people can decide their future. Lai, now vice president, will be inaugurated on May 20.

Speaking to reporters at parliament, Taiwan National Security Bureau Director-General Tsai Ming-yen said maintaining stability in the Taiwan Strait was in the interests of everyone in the international community, including China.

China is currently using a carrot-and-stick approach toward Taiwan, hoping to influence the incoming government's China policy, added Tsai, who shares a common family name with the president but is not related to her.

"What needs special attention is that following May 20, from June to November, is when the Chinese Communists hold their regular military drills," he said. "Whether the Chinese Communists use this hot season as an excuse to carry out some military drills to further pressure Taiwan is a key point the National Security Bureau is focusing on."

China's defense ministry did not answer calls seeking comment outside of office hours on Wednesday, the start of the Labour Day holiday.

China's military has during the past four years massively increased its activities around Taiwan.

NIGHTTIME PATROLS

Taking lawmaker questions, Tsai said China had been observed three times so far this year carrying out "joint combat readiness patrols" at night, something he described as a new development.

"In addition, inflight refueling aircraft are being used during the joint combat readiness patrols" to extend the time combat aircraft can remain in the air, Tsai said.

Landing ships and minesweepers have also been observed joining these patrols, he added.

"These are new patterns for this year."

Taiwan's defense ministry last reported a Chinese combat readiness patrol, where warships and warplanes operate together in the skies and waters near Taiwan, on Saturday.

In 2022, China carried out major war games near Taiwan after a visit to Taipei by then-US House Speaker Nancy Pelosi, and again last year after President Tsai met then-House Speaker Kevin McCarthy on a stopover in California.

Taiwan-based security sources have repeatedly warned China could show their displeasure with Lai using the military.

Since Lai's January election victory, China has kept up a steady stream of pressure on Taiwan, including coast guard patrols near a group of Taiwanese-controlled islands that sit next to the Chinese coast, and opening new air routes in the Taiwan Strait that Taipei says threaten aviation safety.

But Beijing has also offered to resume, albeit in limited form, Chinese tourism to Taiwan, a proposal the government in Taipei is still considering, as it wants a full resumption of visits by Chinese tourists.