There has been intense speculation about the possibility of China launching military exercises in response to Taiwanese President Lai Ching-te's visits to the United States last week.

A senior Taiwanese security official told AFP on Tuesday that "nearly 90" Chinese naval and coast guard vessels had been detected in waters along the so-called first island chain, which links Okinawa, Taiwan and the Philippines.

Taiwan's defence ministry said it had detected 47 Chinese aircraft and 12 warships near the island in the 24 hours to 6:00 am (2200 GMT).

That was the highest number of aircraft detected in a single day since a record 153 reported on October 15, after China staged large-scale military drills in response to Lai's speech days earlier.

Taiwan's defence ministry said Monday its forces were on high alert after Chinese warships and coast guard vessels were spotted near the island and Beijing's People's Liberation Army (PLA) reserved airspace off China's east coast.

There has been no public announcement by the PLA or Chinese state media about increased military activity in the East China Sea, Taiwan Strait or South China Sea.

However, a Beijing foreign ministry spokeswoman said Monday that China would "firmly defend" its sovereignty, as Taiwan kicked off its drills.

Taiwan regards itself as a sovereign nation and has its own government, military and currency.

But Beijing insists the island is part of its territory and has not ruled out using force to bring it under its control.

Lai spoke with Republican US House Speaker Mike Johnson in Guam on Thursday -- the highest-level US contact the Taiwanese leader had during a week-long Pacific trip -- which drew a barrage of criticism from Beijing.

China's foreign ministry warned Taiwan on Friday that "seeking independence with the help of the United States will inevitably hit a wall", and called on Washington to "cease meddling in Taiwan-related affairs".

In response to a question about possible Chinese military drills around Taiwan following his trip, Lai told reporters on Friday that "raising your fists is not as good as opening your hands".

"No matter how many military exercises, warships and aircraft China sends to coerce neighbouring countries, it cannot win the respect of any country," Lai said.

Taiwan faces the constant threat of a military attack by China and relies heavily on US arms sales to boost its defences.

On the eve of Lai's Pacific tour, the United States approved a proposed sale to Taiwan of spare parts for F-16s and radar systems, as well as communications equipment, in deals valued at $385 million in total.