HONG KONG -- Tensions in the South China Sea intensified Wednesday as Vietnamese vessels confronted Chinese ships that were working to place an oil rig off Vietnam's coast, and Vietnamese officials claimed their ships had been rammed by the Chinese vessels three days earlier.
Vietnam said the Chinese ships also fired water cannons at its flotilla in the encounter Sunday, injuring Vietnamese sailors, although Chinese officials did not confirm the incident. The skirmishing highlighted the hair-trigger tensions in the region as Asian nations try to contain China's more aggressive posture in pursuing maritime claims in the South China Sea.
"On May 4, Chinese ships intentionally rammed two Vietnamese Sea Guard vessels," Tran Duy Hai, a Foreign Ministry official, said at a news conference in Hanoi, Vietnam. "Chinese ships, with air support, sought to intimidate Vietnamese vessels."
Last week, the Chinese state oil company Cnooc stationed the oil rig 120 nautical miles off the coast of Vietnam, in waters claimed by China and Vietnam. The placement of the rig led to protests and demands by Vietnam that it be withdrawn, and the deployment of a Vietnamese naval flotilla to the area.
Yang Jiechi, a Chinese state councilor, rebutted the criticisms in a telephone call Tuesday with Deputy Prime Minister Pham Binh Minh of Vietnam. Mr. Yang said the rig was operating within Chinese waters, but Mr. Minh told the Chinese diplomat Vietnam would take "all suitable and necessary measures" to protect its rights and interests, according to the Vietnamese Foreign Ministry.
The incident is the latest chapter in territorial disputes involving China, Vietnam, the Philippines, Brunei and Malaysia. Taiwan also claims swaths of the ocean. The disputes themselves are not new, but an increasingly powerful China with new abilities to reinforce its claims has caused ripples in the region over the last few years. China claims expansive areas of the sea, encompassed in a "nine-dash line" map that critics have said has no basis in international law.
In Washington, a State Department spokeswoman, Jen Psaki, said the United States was concerned about "dangerous conduct and intimidation" in the region. "Given the recent history of tensions in the South China Sea, China's unilateral decision to introduce its oil rig into these disputed waters is provocative and unhelpful," she said at a daily press briefing Wednesday.
In another flare-up, the authorities in the Philippines detained crew members of a Chinese fishing vessel in a disputed area of the South China Sea and accused them of poaching endangered sea turtles.
A Foreign Ministry spokeswoman, Hua Chunying, said China had called upon the Philippines to "immediately" release the fishermen, to "make rational explanations" of its actions and to "take no more provocative action," the Xinhua state news agency reported.