A US destroyer joined the Philippine Navy's flagship for war games that started Thursday close to a flashpoint area of the South China Sea, adding to tensions with China over rival territorial claims.

The exercises are a boost for the Philippines' poorly equipped military as it struggles with perceived rising Chinese aggression, and follows repeated pleas to longtime ally the United States for protection.

"The goal of these exercises is to further boost cooperation... between the two armed forces and further streamline responses to counter-terrorism and maritime security," deputy presidential spokeswoman Abigail Valte told AFP.

The six-day exercises are an annual event but this year they were planned for the west coast of the Philippines' main island of Luzon, close to Scarborough Shoal which China insists it owns.

The shoal is a tiny set of rocks and islets in the South China Sea 230 kilometres (140 miles) east of Luzon and 1,200 kilometres from the nearest major Chinese landmass.

China claims nearly all of the strategically vital South China Sea, even waters close to the shores of its smaller neighbours.

Tensions between China and other claimants to the sea, particularly the Philippines and Vietnam, have escalated in recent years amid a series of Chinese political and military actions to assert its claims to the waters.

The Philippines says China has effectively occupied Scarborough Shoal, a rich fishing ground, for more than a year.

Manila says Chinese vessels now constantly patrol the waters around the shoal, forcing Filipino fishermen who have sailed there for generations to stay away.

Philippine Navy spokesman Lieutenant Commander Gregory Fabic said some of the Philippine-US exercises would be held between Luzon island and the shoal.

Specifically, Fabic said some of the drills would be 108 kilometres east of Scarborough Shoal in "sea lanes of communication within Philippine territory".

Nevertheless, Fabic stressed the war games were not meant to provoke China.

"While the exercises will be between Scarborough Shoal and the main island of Luzon, the focus is inter-operability and not targeted against the Chinese," Fabic told AFP.

Philippine Defence Secretary Voltaire Gazmin, in an unrelated meeting with visiting Japanese counterpart Itsunori Onodera in Manila, said the government was looking at more "high value, high impact" exercises with the United States.

Onodera and Gazmin agreed an increased US military presence in the region would serve to blunt China's influence.

"Both sides agreed that the US presence is (a) very important public asset in East Asia," Onodera said.

The Cooperation Afloat Readiness and Training (CARAT) exercises will involve three US Navy vessels, including the USS Fitzgerald, a guided missile destroyer, according to a Philippine Navy statement.

The Philippines will deploy its flagship, a former US coastguard cutter called the Gregorio del Pilar, as well as other navy and coastguard vessels.

About 500 US forces and another 500 Filipino troops will take part in the exercises, according to Fabic.

He said among the highlights was an exercise designed to intercept suspected enemy ships, board them and seize materials they may be carrying that could pose a danger to allies.

There will also be simulated counter-terrorism exercises, as well as training in disaster response and increasing proficiency in naval gunnery, he added.

Malaysia, Brunei and Taiwan also claim parts of the South China Sea, which is believed to sit atop vast deposits of fossil fuels, and the area has for decades been regarded as a potential trigger for major military conflict.

China has consistently reacted with anger at Philippine efforts in recent years to hold onto the territory claimed by both countries.

The Chinese embassy in Manila released a statement on Thursday cautioning the Philippines and the United states not to exacerbate tensions in the area with its exercises.

"We hope relevant sides should take actions that are beneficial for maintaining peace and stability in the region, not the other way around," the statement said, citing a foreign ministry spokesman in Beijing.

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