China sent 39 warplanes -- mostly fighter jets -- into Taiwan's air defence zone on Sunday, the island's government said, in the largest daily incursion since October.

Taiwan lives under the constant threat of invasion by China, which sees the self-ruled, democratic island as part of its territory to eventually be reclaimed, by force if necessary.

The final quarter of 2021 saw a massive spike of incursions from China into Taiwan's air defence identification zone (ADIZ), with the biggest single day coming on October 4, when 56 Chinese warplanes entered the zone.

Taiwan's defence ministry said in a statement late Sunday it scrambled its own aircraft to broadcast warnings and deployed missiles to track 39 Chinese jets that entered the ADIZ.

The incursions included 24 J-16 fighters -- which experts say are among China's favourite jets for testing Taiwan's air defences -- 10 J-10 fighters and one nuclear-capable H-6 bomber.

Taiwan only started regularly publicising its data on air incursions in September 2020.

October remains the busiest month on record, with 196 incursions, 149 of which were made over just four days as Beijing marked its annual National Day.

The defence zone is not the same as Taiwan's territorial airspace but includes a far greater area that overlaps with part of China's own ADIZ.

Beijing has ramped up pressure on Taiwan since Tsai Ing-wen was elected president in 2016, as she views the island as a sovereign nation and not part of "one China".

Last year, Taiwan recorded 969 incursions by Chinese warplanes into its ADIZ, according to a database compiled by AFP -- more than double the roughly 380 carried out in 2020.

Taiwan's air force has suffered a string of fatal accidents in recent years as its ageing fleet is kept under constant pressure by China.

The air force temporarily grounded all F-16 fighters earlier this month after one of its most advanced F-16V jets crashed into the sea during a routine training mission, killing one pilot.