MANILA, Philippines — China warned Asian neighbors Thursday to stop searching for oil near the Spratly Islands and vowed to assert its sovereignty over the potentially petroleum-rich territory in the South China Sea that several nations claim.
China and the Philippines have swapped diplomatic protests over the islands, with Filipino officials accusing Chinese forces of intruding into Manila-claimed areas six times since February and of firing shots at least once. Beijing denied the allegation Thursday and said it would use violence only when attacked.
Vietnam, meanwhile, has accused China of flaring tensions in Vietnamese waters by hindering the operation of a oil and gas exploration boat for the second time in two weeks.
The Spratlys, which are believed to be atop vast oil and gas reserves, have long been feared as a potential flash point of armed conflict in Asia.
The chain of barren, largely uninhabited islands, reefs and banks are claimed wholly by China, Taiwan and Vietnam and partly by the Philippines, Malaysia and Brunei.
Addressing Manila's complaints for the first time, Chinese Ambassador Liu Jianchao denied that his government committed any intrusion.
He said China has not started to drill for oil there and warned others to stop any oil exploration in the area without Beijing's permission. China claims the entire South China Sea.
"We're calling on other parties to stop searching for the possibility of exploiting resources in these areas where China has its claims," he told reporters.
He said China is open to engaging other countries in joint oil and gas exploration.
Asked what would happen if countries defy China, Liu said that Beijing would assert its right over the disputed region diplomatically. "We will never use force unless we are attacked," he said.
In Vietnam, Foreign Ministry spokeswoman Nguyen Phuong Nga said in a press briefing Thursday that a Chinese fishing boat supported by two patrol vessels that morning damaged the exploration cable of the seismic survey boat operated by state-owned PetroVietnam.
She said the actions of the Chinese boats were "completely premeditated" and "seriously violating Vietnam's sovereign rights."
The incident came just two weeks after Chinese patrol boats cut another cable on a survey boat off its central coast. Hanoi says both incidents occurred well within the 200 nautical miles guaranteed to Vietnam as an exclusive economic zone by international law.
Nga said Vietnam's Foreign Ministry officials met Thursday with Chinese Embassy officials to lodge protests. Last weekend, in rare protests spurred by Facebook and text messages, thousands of Vietnamese took to the streets in Hanoi and Ho Chi Minh City, demanding that China stay out of Vietnamese waters.
In the most serious incident reported by the Philippines, a Chinese navy vessel allegedly fired Feb. 25 to scare away Filipino fishermen from Jackson Atoll, which is claimed by Manila and relatively close to the Philippine shore.
The Philippine government also accused two Chinese patrol boats of harassing a Philippine oil exploration ship on March 2 into leaving a vast area called the Reed Bank. A Philippine general scrambled two military aircraft, which arrived after the Chinese vessels had left, the Philippine military said.
Liu said no Chinese vessel fired on Filipino fishermen but suggested that Chinese forces took action to keep the exploration ship from the Reed Bank.
"That's part of our exercise of jurisdiction. It's not harassment," Liu said.
Liu said some of Manila's allegations were sparked by rumors, like a claim that Chinese fighter jets flew near Philippine patrol planes over Spratly islands claimed by Manila. Chinese foreign ministry spokesman Hong Lei said Tuesday the Philippines "should stop publishing irresponsible statements that do not match the facts."
President Benigno Aquino III's spokesperon, Edwin Lacierda, countered Thursday that the Philippines would firmly assert its territorial claims "at every opportunity and in a manner befitting a free, sovereign nation."
Lacierda added that Manila would take a "multilateral approach" — in contrast to China's position of bilateral negotiations — to resolve the disputes.
The tug-of-war over the islands has raised questions about whether the United States, a key Philippine military ally, could participate in solving the disputes.
David Carden, Washington's ambassador to the Association of Southeast Asian Nations, said last month in Manila that the Spratly claimants need to create a strong regional mechanism to tackle the dispute, and that the U.S. could help.
Liu, however, said the U.S. "is not a party to the disputes" and China would talk only with those countries that were.
Liu also dismissed U.S. concerns that the dispute over tSpratlys could hamper the passage of commercial ships in the South China Sea, home to some of the world's busiest sealanes.
"These maritime waters have always been peaceful and secure," he said.