Taiwan reported the largest ever incursion by China’s air force into its air defence zone on Monday at 52 aircraft, saying the Taiwanese air force had to scramble for the fourth straight day to warn off the intruders, as tensions spiralled.

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.

But since Friday, when China marked its national day, the country has embarked upon a massive ramping up of its missions, with almost 150 aircraft flying into the defence zone over the space of four days.

The US department of defence said on Monday that China’s increasing military activities conducted near Taiwan are destabilising and increase the risk of miscalculation.

“Our commitment to Taiwan is rock-solid and contributes to the maintenance of peace and stability across the Taiwan Strait and within the region,” it said in a statement.

The latest mission included 34 J-16 fighters and 12 nuclear-capable H-6 bombers, which all flew in an area in the vicinity of the Pratas Islands, according to a map provided by the ministry.