By Manuel Mogato
PUERTO PRINCESA CITY, Philippines (Reuters) - The Philippines will hold separate naval exercises with U.S. and Japanese forces this week on a Philippine island that is not far from the disputed Spratly archipelago, where China's rapid creation of seven island outposts is stoking regional tensions.
Manila, which has one of the weakest navies in Asia, has stepped up its security cooperation this year in the wake of Chinese assertiveness in the South China Sea, not just with ally Washington, but also with Japan and Vietnam.
A Philippine military official said there was no plan for the Philippine, U.S. and Japanese navies to hold combined exercises on Palawan island, 160 km (100 miles) from the Spratlys, although the drills could intersect because Manila had limited naval assets.
"At some point all three forces could merge in one activity because we only have two ships and limited aircraft to take part in these exercises," said the official, who declined to be identified.
Late on Sunday, reporters could see two P3C-Orion maritime surveillance planes, one belonging to the United States and the other Japan, parked on a military airfield in Puerto Princesa City, the Palawan capital.
The two-week exercises with the United States began late last week. The two-day drills with Japan start on Tuesday, officials said. Both will take place in Philippine territorial waters, not part of the contested South China Sea.
While the Philippine military trains regularly with U.S forces, it only held its first joint naval drills with Japan in May.
Tokyo has no territorial claims in the South China Sea, but it worries about becoming isolated should China dominate a waterway through which much of Japan's ship-borne trade passes.
Prime Minister Shinzo Abe's government has beefed up security cooperation across Southeast Asia this year.
China claims most of the South China Sea. The Philippines, Malaysia, Vietnam, Taiwan and Brunei have overlapping claims.
Beijing said last week that some of its reclamation work in the Spratlys would be completed soon but that it would continue to build facilities on the reefs it occupies.
It says the outposts will have undefined military purposes as well as help with maritime search and rescue, disaster relief, environmental protection and navigation.
(Additional reporting by Tim Kelly and Nobuhiro Kubo in TOKYO; Writing by Dean Yates; Editing by Michael Perry)