BEIJING - China on Tuesday urged Vietnamese government to take effective measures to stop its fishermen from illegal fishing in waters off the Xisha Islands in the South China Sea.

Foreign Ministry spokesman Hong Lei made the remarks in response to allegations from his Vietnamese counterpart on Monday that a Chinese vessel fired on a Vietnamese fishing boat in waters off the Xisha Islands last Wednesday.

Vietnam demands China investigate and seriously deal with the incident, and compensate Vietnamese fishermen for their loss, said Vietnamese Foreign Ministry spokesman Luong Thanh Nghi.

The Xisha Islands are Chinese territory, said Hong, adding that China's sovereignty over the islands is indisputable.

China's actions toward the Vietnamese fishing boat were necessary and justified, as the boat had operated illegally in waters off China's Xisha Islands, according to the spokesman.

He said that checks with relevant authorities had verified that China's action caused no damage to the Vietnamese boat.

China urges Vietnam to take effective measures to strengthen education and management of its fishermen, and stop them from illegal activities, said Hong.