The Philippines said Friday it planned to defy Chinese warnings and pursue a case in the United Nations challenging Beijing's claim to most of the South China Sea.
Manila is to file as scheduled its "memorial", or formal pleading on Sunday, which would allow the U.N. arbitral tribunal to study the Philippine argument that the Chinese claim covers parts of Filipino territory, officials said.
Abigail Valte, a spokeswoman for President Benigno Aquino, said the government was pursuing the case despite official Chinese warnings of fallout in bilateral relations.
"At least for the Philippine government we can say that all factors have been taken into consideration when the discussions were being had on the matter of the arbitration," she told reporters.
China claims most of the strategically important body of water as well as islets and reefs which border major sea lanes and are reputed to sit on vast oil and gas reserves.
The Philippines, whose forces are dwarfed by its giant neighbor in an increasingly tense stand-off over some reefs and shoals, sought U.N. arbitration in January 2012 to settle the dispute, but China has rejected the move.
China's foreign ministry spokesman Hong Lei warned the Philippines on Wednesday against proceeding with the U.N. case.
"China will never accept nor participate in the international arbitration unilaterally initiated and pushed by the Philippines, and China's position has a solid basis in international law," Hong told a news conference in Beijing.
"We hope that the Philippine side... returns to the right track of resolving the dispute through negotiation and consultation as soon as possible, (and) stops going any further down the wrong track so as to avoid further damage to bilateral relations."
Valte said the Aquino government was aware the U.N. tribunal may not be able to enforce its ruling if it decides against China.
"(But) at least assuming that a favorable decision (for the Philippines) is rendered, then that is additional weight for the Philippine position," she said.
The Philippine case alleges that Chinese claims to areas of the South China Sea and its seabed cover areas as far as 870 nautical miles (1,611 kilometers) from the nearest Chinese coast, and are thus illegal under the U.N. Convention on the Law of the Sea.
Both countries are signatories to the 1982 treaty.
In the latest hostile encounter between the two, Chinese coastguard ships this month blocked two Filipino-flagged vessels headed for Second Thomas Shoal in the Spratly group, around 200 kilometers (125 miles) from the western Philippine island of Palawan.
The Philippines said the vessels were bringing supplies to Filipino marines aboard a decrepit navy ship that it beached on the shoal in 1999.
The Philippine has also accused China of firing water cannon at Filipino fishermen near Scarborough Shoal, another South China Sea outcrop.
