MANILA, Feb. 20 (CNA) - A joint air patrol by the Philippines with the United States was aimed at protecting territory and national interests in the South China Sea, a Philippine military official said on Tuesday (Feb 20), after Beijing accused Manila of stirring up trouble.

Philippine fighter jets and a US bomber plane flew together over the South China Sea on Monday, more than a week after their navies held joint maritime exercises in the face of simmering tensions over territorial claims in the area.

"This is to enhance both armed forces' interoperability and enhance the capabilities of our air force (in) performing its mandate of protecting our territory, sovereign rights and national interests," armed forces public affairs chief Xerxes Trinidad said.

China's military earlier accused the Philippines of "stirring up trouble" by conducting a joint air patrol with "extraterritorial countries" and then openly "hyping it up".

Its Southern Theater Command said it organised frontline naval and air forces to closely monitor the joint drills on Monday, and that troops "maintained a high degree of vigilance to resolutely defend national sovereignty".

China claims sovereignty over almost the entire South China Sea, a conduit for more than US$3 trillion of commercial shipping annually, including parts of the exclusive economic zones of the Philippines, Vietnam, Indonesia, Malaysia and Brunei.

Philippine ties with China have deteriorated this past year at a time when Manila is expanding its longstanding defence relationship with former colonial power the United States under President Ferdinand Marcos Jr.

The Philippines refrained from joint air and sea exercises in the South China Sea under his anti-US predecessor Rodrigo Duterte, who advocated closer relations with Beijing and saw defence activities with Washington as provocative.

Trinidad said the Philippines expects to carry out more joint maritime activities with its ally and other "like-minded" partners to keep a peaceful Indo-Pacific.

Photo from Reuters