Beijing and Taipei on Thursday dismissed Manila's renaming part of the South China Sea as the "West Philippine Sea", with both saying the designation did not affect their own sovereignty claims.
Beijing asserts its sovereignty over nearly all of the South China Sea, even waters approaching the coasts of other countries, while the Philippines, Vietnam, Malaysia, Brunei and Taiwan have overlapping claims.
On Wednesday, Philippines President Benigno Aquino announced that his government had officially dubbed the waters off the country's west coast the "West Philippine Sea" and would register the name with the United Nations.
China's foreign ministry spokesman Hong Lei told reporters: "The act by the Philippines cannot in the least way change the fact that China has indisputable sovereignty over the islands in the South China Sea and adjacent waters.
"For a long time the South China Sea has been a geographic name universally accepted by the international community and widely used by countries the world over, including the United Nations and other international organisations," he added.
In Taipei, the foreign ministry said in a statement that Taiwan "does not recognise this unilateral move that will provoke disputes and sternly reaffirms its territorial claim" to the sea.
"We urge neighbouring countries to exercise self-restraint and avoid any unilateral moves that will affect peace and stability in the region, instead replacing confrontation with dialogue," it said.
Strategically important shipping routes run through the sea and it is thought to harbour large petroleum reserves.
The rival claims make the area a potential military flashpoint and earlier this year Chinese and Filipino ships engaged in a stand-off at Scarborough Shoal.
The rocky outcrop sits about 230 kilometres (140 miles) from the west coast of the Philippines' main island of Luzon, while the nearest major Chinese landmass is 1,200 kilometres northwest, according to Philippine navy maps.
The Philippines defended its latest move, with Aquino's spokesman Edwin Lacierda saying the renaming should not be a "cause of conflict" with its neighbours.
"How does one threaten other nations when what we've called the West Philippine Sea covers (our) exclusive economic zone?," he said.