MELBOURNE, Australia: Southeast Asian and Australian leaders on Wednesday warned against actions that "endanger peace" in the South China Sea, following fresh confrontations between Beijing and the Philippines in contested waters.

Simmering tensions in the trade corridor threatened to boil over this week, when Chinese boats in the Spratly Islands were accused of hounding Philippine vessels.

Beijing on Wednesday accused the United States of using the Philippines as a "pawn to stir up trouble in the South China Sea" as hostilities between the Asian nations escalate over their territorial dispute.

China claims almost the entirety of the South China Sea as its own, ignoring legal precedents and competing claims from a host of Southeast Asian nations.

The festering dispute poses one of the region's most vexing security challenges, looming large during a three-day summit between Australia and the 10-nation Asean bloc.

"We encourage all countries to avoid any unilateral actions that endanger peace, security and stability in the region," read a joint declaration hammered out between Asean members and Australia.

"We recognize the benefits of having the South China Sea as a sea of peace, stability and prosperity," the statement added.

As the summit kicked off on Monday, Philippine Foreign Minister Enrique Manalo delivered a simple request to Beijing: "Stop harassing us."

The following day, Chinese coast guard boats were accused of harassing a flotilla of Philippine ships sailing on a resupply mission.

The Chinese vessels were involved in two separate collisions, the Philippines coast guard said, and blasted one of the resupply boats with a water cannon.

Images taken in the aftermath showed the water cannon had shattered windows on the control bridge of one of the Philippine vessels.

Bound to act by consensus, the Asean forum has long struggled to make inroads on the overlapping claims staked throughout the South China Sea.