At around 10:30 a.m. Sunday, the 1st Fisheries Resources Surveillance Force based in the northern city of Hai Phong dispatched two patrol ships to stop the illegal fishing after spotting many foreign ships trespassing in the Gulf of Tonkin near Bach Long Vy Island.

The fishing boats fled towards China. Among them are two steel-hulled vessels with Chinese flags.

The Vietnamese ships sped up and sprayed water cannons to drive the vessels away, even as Vietnamese officers issued warnings and ordered the Chinese fishermen to stop illegally fishing in Vietnamese waters.

Vo Khoi Thanh, deputy head of the 1st Fisheries Resources Surveillance, said foreign steel-hull vessels, many of them from China, have been taking advantage of bad weather and poor visibility to trespass into Vietnamese waters for illegal fishing.

"Though the Chinese-flagged fishing boats were chased from Vietnamese waters but they still could return. In order to protect Vietnam’s sovereignty, maritime territory and exclusive economic zone, Vietnamese surveillance ships have to increase patrolling of the waters," Thanh said.

Last month, Chinese vessel numbered 44101 rammed and sank a Vietnamese fishing boat while it was fishing in the Da Loi (Discovery) Reef off Vietnam’s Hoang Sa (Paracel) Archipelago, according to the National Committee for Incident, Natural Disaster Response and Search and Rescue.

Following the incident, the Ministry of Foreign Affairs handed over a diplomatic note to representatives from the Chinese embassy in Hanoi to protest the Chinese vessel’s action and demanded due compensation for Vietnamese fishermen.