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 retaken, by force if necessary.

On Tuesday, 29 Chinese aircraft -- including 17 fighter jets and six bombers -- crossed into Taiwan's air defence identification zone (ADIZ), Taipei's defence ministry said.

The ministry added that it scrambled its own aircraft to broadcast warnings and deployed air defence missile systems to track the jets.

It marked this year's third-biggest daily incursion by Chinese warplanes, after 39 jets entered the zone on January 23 and 30 jets on May 30, according to a database compiled by AFP.

The final quarter of 2021 saw a spike in ADIZ incursions, with the biggest single-day breach on October 4 when 56 warplanes entered the zone.

October 2021 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.

China has ramped up pressure since Tsai Ing-wen was elected president in 2016, as she considers Taiwan a sovereign nation.

Last year, Taiwan recorded 969 sorties by Chinese warplanes into its ADIZ, according to the AFP database -- more than double the roughly 380 carried out in 2020. The figure for this year so far already exceeds 500.

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