Vietnam on Tuesday said it had formally complained to Beijing over claims Chinese fishing vessels sabotaged a boat owned by energy giant PetroVietnam in the latest tensions over the disputed South China Sea.
Beijing must "immediately end this wrongdoing and not allow similar acts to reoccur", Ministry of Foreign Affairs spokesman Luong Thanh Nghi said in a statement. He added that the incident "violated Vietnam's sovereignty".
PetroVietnam's geological survey vessel, the Binh Minh 2, was operating in Vietnamese territorial waters on Friday when it was approached by a number of Chinese fishing vessels which cuts its exploration cables, Vietnam News reported.
Vietnam and China have a long-standing dispute in the South China Sea over their competing claims to the Paracel and Spratly islands, both potentially resource-rich rocky outcrops that straddle key shipping lanes.
Beijing last week announced new rules, which appear to allow police to board foreign ships in the disputed South China Sea.
Vietnamese Prime Minister Nguyen Tan Dung has also signed a decree authorising a new "specialised force" to be deployed from January 25 to stop foreign vessels that violate fishing laws in Vietnam's waters, according to a post on the government's official website on Friday.
The South China Sea is strategically significant, home to some of the world's most important shipping lanes and believed to be rich in resources. Vietnam has begun exploring for oil in what it claims as its territorial waters.
The PetroVietnam standoff is the second such incident in 18 months, with Chinese vessels accused of cutting the cables of the Binh Minh 2 in May last year, prompting Hanoi to demand compensation from Beijing.
China's increasingly assertive role in the South China Sea has raised tensions with other countries in the region as well as the United States.
Last week, Vietnamese border guards told AFP they were refusing to stamp entry visas in China's controversial new passports, which feature a map of Beijing's claim to almost all of the South China Sea.
Other claimants to parts of the South China Sea are Brunei, Malaysia and Taiwan.