A statement released by the Chinese foreign ministry on Sunday said that Vietnam had sent dozens of ships into the disputed territory in an illegal operation carried out on Saturday.

"As of 5 pm on 7 June, there were as many as 63 Vietnamese vessels in the area at the peak, attempting to break through China's cordon and ramming the Chinese government ships for a total of 1,416 times," the statement said.

"In the face of Vietnam's provocative actions on the sea, China exercised great restraint and took necessary preventive measures," it added.

There was no immediate response to the accusation from Vietnam.

Oil rig in disputed waters

Tensions in the region have been heightened since early May, when China towed an oil rig into an area of the South China Sea claimed by both Beijing and Hanoi as their sovereign territory.

The move triggered anti-Chinese riots in Vietnam last month and in the most serious incident so far, a Vietnamese fishing boat sank on May 26 during a confrontation not far from the oil rig.

pfd/hc (dpa, Reuters)