Hundreds of demonstrators in Vietnam gathered at the Chinese embassy in Hanoi Sunday, demanding that China stay out of waters claimed by Vietnam.
Police allowed the mostly young demonstrators to protest peacefully for awhile before dispersing them.
The rare demonstration came after Vietnamese officials said a Chinese patrol vessel intentionally cut a submerged cable last month, towed by a ship operated by the Vietnam National Oil and Gas Group. The survey ship was conducting seismic tests in disputed waters in the South China Sea.
Vietnam's Foreign Affairs Ministry accused Beijing of violating Vietnam's sovereignty right to its continental shelf, while China responded that it opposes Vietnam's exploration for oil and gas in what Beijing called China's jurisdictional area.
China, Vietnam, the Philippines, Malaysia, Brunei and Taiwan all claim South China Sea territories, which are thought to hold untapped oil and gas reserves.
The Association of Southeast Asian Nations has been seeking a peaceful solution to the competing claims amid increasingly assertive actions by China.