Australia and the Philippines began joint air and naval patrols in the South China

Sea on Saturday, in an effort to bolster strategic cooperation in countering China's assertiveness in the region.

In a joint statement, Australia and the Philippines said the three-day patrols showed their "shared commitment to exercising freedom of navigation and overflight consistent with international law."

"Australia and the Philippines are firmly committed to peaceful, secure and prosperous region, where sovereignty and agreed rules and norms are respected," Australian Deputy Prime Minister Richard Marles said in the statement. 

Philippine President Ferdinand Marcos Jr. said that the joint patrols were "a practical manifestation of the growing and deepening strategic and defense partnership" between Australia and the Philippines. 

"We endeavor to enhance bilateral interoperability in maritime security and domain awareness," Marcos said on the social media. 

During the patrolling exercise, the Philippines will deploy two navy ships and five surveillance airplanes along with Australia's HMAS Toowoomba warship and a P-8A maritime surveillance aircraft.

The sea patrols will be conducted inside the Philippines exclusive economic zone (EEZ), the Philippine Department of National Defense spokesperson Arsenio Andolong said.

The Philippines' EEZ extends 200 nautical miles (370 km) from the shore into the South China Sea, and into waters claimed by China 

Philippines on guard amid Chinese 'aggression'

The increased frequency of air and maritime patrols follow heightened tensions over territorial disputes in the South China Sea — almost all of which China claims as its own territory, disregarding international tribunal's ruling in 2016 that its claims have no legal basis.

The announcement of patrols with Australia come just a few days after it held a similar exercise with the US in the South China Sea.

China regularly patrols the region and has built artificial islands where it has deployed its military to reinforce its claims.

Last month, a Chinese coast guard ship rammed a Philippine fishing vessel in contested waters near Second Thomas Shoal, spiking tensions between the two countries.

Marcos warned on Sunday that the Chinese military had "started to show interest" in building bases on reefs that were "closer and closer to the Philippine coastline."

mfi/wmr (AFP, Reuters)