Beijing views democratic self-ruled Taiwan as its own territory and has vowed to one day seize it, by force if necessary.

Taiwan's air force said its planes broadcast warnings and "took active intercept responses" as China's J-10 fighter briefly flew into the island's southwestern air defence identification zone (ADIZ).

The latest incursion came a week after multiple Chinese Su-30 jets entered Taiwan's ADIZ last Tuesday, hours after a US military transport plane flew over the island in a move that China called an "illegal act" and "serious provocation".

A Chinese military Y-8 transport aircraft also briefly entered Taiwan's defence zone on Friday.

The ADIZ stretches beyond Taiwan's airspace and is used to give an early warning of possible incursions. China maintains a similar air defence zone.

Beijing has ramped up fighter flights and military exercises near Taiwan since the 2016 election of President Tsai Ing-wen, who refuses to acknowledge that the island is part of "one China".

It has also sought to diplomatically and economically isolate the island.

Tsai was elected for a second term in January with a record landslide in a vivid rebuke of Beijing's hardline stance.

In February, she criticised Beijing for a "meaningless and unnecessary" move when a fighter jet crossed the median line of the Taiwan Strait separating the two sides.

In March 2019, two Chinese J-11 fighter jets crossed over the median line for the first time in years.

Beijing also sent its new aircraft carrier, the Shandong, through the strait in December, shortly before Taiwan's presidential election.