Taiwan sharply criticised China on Saturday after Beijing marked the founding of the People’s Republic of China with the largest ever incursion by the Chinese air force into the island’s air defence zone.

Chinese-claimed Taiwan has complained for a year or more of repeated missions by China’s air force near the democratically governed island, often in the southwestern part of its air defence zone close to the Taiwan-controlled Pratas Islands.

Taiwanese fighters scrambled against 38 Chinese aircraft in two waves on Friday, the Taiwan Defence Ministry said. It said Taiwan sent combat aircraft to warn away the Chinese aircraft, while missile systems were deployed to monitor them.

“China has been wantonly engaged in military aggression, damaging regional peace,” Taiwan Premier Su Tseng-chang told reporters on Saturday morning.

The first wave of incursions comprised 18 J-16 and four Su-30 fighter jets plus two nuclear-capable H-6 bombers and an anti-submarine aircraft, while the second had 10 J-16s, 2 H-6s and an early warning aircraft, the ministry said.

The first batch of Chinese aircraft all flew in an area close to the Pratas Islands, with the two bombers flying closest to the atoll, according to a map issued by the ministry.

The second group flew down into the Bashi Channel that separates Taiwan from the Philippines, a key waterway that links the Pacific with the disputed South China Sea.

China has yet to comment. It has previously said such flights were to protect the country’s sovereignty and aimed at “collusion” between Taiwan and the United States, the island’s most important international backer.

The previous largest incursion happened in June, involving 28 Chinese air force aircraft.

China’s latest mission came less than a day after its government launched a attack on Taiwan’s foreign minister, evoking the words of revolutionary leader Mao Zedong to denounce him as a “shrilling” fly for his efforts to promote Taiwan internationally.

China has stepped up military and political pressure to try and force Taiwan to accept Chinese sovereignty.

Taiwan says it is an independent country and will defend its freedom and democracy.