MANILA  - Vietnamese Prime Minister Nguyen Tan Dung said Wednesday that China's placing of an oil rig in contested East Vietnam Sea waters had "seriously threatened peace".

Speaking in Manila after meeting Philippine President Benigno Aquino, Dung said the leaders agreed that China should be condemned by the international community for the oil rig deployment and many other illegal actions in the sea.

"With regard to the situation in the East Sea, the president and I shared the deep concerns over the current extremely dangerous situations caused by China's many actions that violate international law," Dung said, standing alongside Aquino at the presidential palace.

"In particular, China's illegal placement of the oil rig Haiyang 981 and deployment of escorting vessels to protect the rig... have seriously threatened peace, stability, maritime security and safety and freedom of navigation in the East Sea."

China claims nearly all of the sea, even waters approaching the coasts of its neighbours.

Vietnam, the Philippines, Brunei and Malaysia, as well as Taiwan, have competing claims to parts of the sea, and the disputes have for decades made it a potential trigger for conflict.

Tensions have risen in recent years as Vietnam and the Philippines have accused China of becoming increasingly aggressive in asserting its claims to the waters.

Anti-China rage erupted in Vietnam last week because of the oil rig deployment, as dozens of Chinese and Vietnamese vessels engaged in repeated skirmishes in the hotspot area.

Four Chinese nationals died in last week's riots, according to China, which has insisted it has indisputable sovereign rights to all of the contested waters.