Beijing on Wednesday expressed opposition to Washington's emboldening of Manila's latest infringements and provocations in the South China Sea, urging the United States not to use the Philippines as a pawn to muddy waters in the area.

Chinese Foreign Ministry spokeswoman Mao Ning made the response after the spokesperson of the US Department of State on Tuesday condemned China of repeatedly obstructing Philippine vessels' maritime operations in the South China Sea.

The US' remarks came as China's Coast Guard took necessary law enforcement measures against Philippine vessels that intruded into the adjacent waters of Ren'ai Reef in Nansha Islands on Tuesday.

The vessels tried to transport supplies, including construction materials, to the military vessel illegally grounded at the reef.

"In this incident, it is clear who is the one that makes provocations to create trouble, as well as violating international law and undermining peace and stability in the South China Sea," Mao said at a daily news conference.

Disregarding truth

In disregard of the truth, the US State Department confuses right and wrong to make "baseless attacks against China's legitimate and lawful actions to safeguard our rights", she said.

"It has arbitrarily threatened China by resorting to the US-Philippines Mutual Defense Treaty to embolden the Philippines and endorse its acts of infringement and provocation," she said, adding that Beijing firmly opposes such moves.

China has indisputable sovereignty over Nansha Islands and its adjacent waters, including Ren'ai Reef, she said.

Stressing that the issue regrading Ren'ai Reef is a bilateral one between China and the Philippines, Mao said it allows no provocation or interference from any third party, including the US.

China is firm in its resolve to safeguard its legitimate rights, and the Philippines' infringements and provocations will not succeed, she said.

"We hope that the Philippines will stop acting as a pawn for the US to disrupt the South China Sea," she said. "Lessons from history tell us that pawns will be abandoned in the end."