Philippine coast guard personnel aboard ship (right) and a rubber boat take positions during a simulation of a sea jacking scenario as part of the combined Philippine-Japan maritime exercise off Manila bay, in the mouth of South China sea, on Wednesday. 

Reuters/Aboard BRP Batangas, Philippines

Philippine and Japanese coast guard teams staged an anti-piracy drill on Wednesday, featuring the storming of a cargo vessel after a mock hijack, in a show of maritime cooperation between the two nations amid rising tension in Asian waters.

Both nations face a challenge from China's growing assertiveness over territorial claims in the South China Sea and the East China Sea, where it uses coast guard and fishing vessels to press into disputed areas.

Wednesday's drill was the first held by Japan and the Philippines after signing a strategic partnership pact in 2012.

The exercises in Manila Bay were watched by the coast guard chiefs of 17 Asian nations, including China, who are meeting to find ways to cooperate in boosting safety and battling piracy and transnational crime.

Japan has been helping the Philippines improve its skills in maritime law enforcement, safety and environment protection, Captain Koichi Kawagoe of Japan's coast guard told reporters.

"This exercise is for mutual interest, such as pirates and illegal trafficking, drug trafficking, firearms trafficking," Kawagoe said, adding that Japan was ready to help Southeast Asian nations, even in the disputed South China Sea.

"As long as the incident is related to piracy, we will coordinate our efforts."

Asked about the drills, Chinese Foreign Ministry spokeswoman Hua Chunying said in Beijing she hoped countries in the region could "do more to increase mutual trust and maintain regional peace and stability".

China claims most of the potentially energy-rich South China Sea, through which $5tn in ship-borne trade passes every year. The Philippines, Vietnam, Malaysia, Brunei and Taiwan also have overlapping claims.

China has rejected diplomatic protests by the Philippines and Vietnam and criticism from the US over its reclamation work on reefs and tiny islands, saying it falls "within the scope of China's sovereignty".

Last month, China's coast guard fired water cannon on Philippine fishermen in a disputed shoal. In the past, it has challenged Japan's coast guard near a disputed island in the East China Sea.

Later this year, the Philippines will take delivery of the first of ten 40-metre patrol boats Japan is building, said Coast Guard spokesman Commander Armand Balilo.