TAIPEI (AFP) - Taiwan's air force scrambled fighter jets to track two Chinese Y-8 maritime patrol aircraft which intruded into the island's airspace, a senior air force officer said on Tuesday.

One plane entered Taiwan's ADIZ (air defence identification zone) at 8:33am on Monday and another at 2:31 pm, en route to a disputed area in the South China Sea.

The planes had taken off from the mainland's southeastern province of Guangdong. Taiwan scrambled Mirage 2000-5s and Indigenous Defence Fighters.

"We followed them closely to make sure they left our ADIZ," Air Force Major General Hsiung Hou-chi told reporters, declining to say how many fighters were mobilised in the two missions.

The United Daily News cited an unidentified military officer as saying that Chinese aircraft had detoured in the past so as not to enter Taiwan's ADIZ.

By entering it this time the Chinese air force could test Taiwan's air surveillance capabilities and its reaction to intruders, the officer said.

The incident came amid speculation that China may set up an ADIZ in the South China Sea to assert its territorial claims.

Last year it declared an ADIZ in the East China Sea that included islands also claimed by Japan.

Tensions between Taiwan and the Chinese mainland have eased markedly since Ma Ying-jeou of the China-friendly Kuomintang party came to power in 2008. He was re-elected in January 2012.

However, China still refuses to renounce its use of force against Taiwan should the island declare independence.