China has flown more than 30 military planes toward Taiwan, the second large display of force in as many days.
Taiwan's Defence Ministry on Saturday said 39 aircraft entered Taiwan's air defence identification zone in two sorties, one during the day and one at night.
That followed a similar pattern on Friday, when 38 planes flew into the area south of the self-governing island.
China claims Taiwan, which lies off its east coast, as its territory.
The two split in 1949 during a civil war in which the Communists took control of mainland China and the rival Nationalists set up a government on Taiwan.
Mass incursions used to be rare.
But in the last two years Beijing has begun sending large sorties into Taiwan's ADIZ to signal dissatisfaction at key moments - and to keep Taipei's ageing fighter fleet regularly stressed.
Last week 24 Chinese warplanes flew into the area after Taiwan applied to join a major trans-Pacific trade pact.
Alexander Huang, associate professor at Tamkang University in Taipei, said he believed the latest aerial incursion was not just about sending a message to Taiwan.
"There's three other carrier attack groups in the region, two American and one British," he told AFP.
"China is sending a political message to the US and UK on her national day: Don't mess around in my area."
Canadian, French and Australian warships have all made voyages through the Taiwan Strait in recent years, sparking protests from China.
Additional reporting: AFP
