Vietnam has accused China of damaging a fishing boat in the latest escalation of tension in the disputed South China Sea.

The Foreign Ministry said a Chinese vessel slammed into a Vietnamese fishing boat while it was operating in Vietnamese waters on May 20. It damaged the ship's hull and risked the lives of 15 crew members, it said.

Ministry spokesman Luong Thanh Nghi said in a statement that the ministry lodged a protest Monday with the Chinese embassy.

Nghi said the Chinese action violated Vietnam's sovereignty and demanded that China severely punish the violators, compensate the fishermen and make sure similar incidents do not occur.

Chinese Foreign Ministry rejected the charges.

"Vietnam's accusations against China are totally untrue. The Vietnamese fishing boat entered waters around China's Xisha islands and fished illegally in violation of China's sovereignty and laws," Foreign Ministry spokesman Hong Lei said, referring to the Paracel islands. "There is nothing to dispute about China's relevant authorities carrying out normal law enforcement. We demand that Vietnam take concrete measures to educate fishermen to stop fishing illegally."

Vietnam said in March that a Chinese naval vessel fired flares that damaging a fishing boat's cabin near the islands.