Vietnam has accused a Chinese vessel of firing on one of its fishing boats in disputed waters in the South China Sea, setting it alight.
Vietnamese foreign ministry said the “very serious incident” took place on March 20 near the Paracel islands.
Its statement did not specify what kind of Chinese vessel was involved.
Vietnam and China both claim the Paracel islands, which have been controlled by China since a short war with South Vietnam in 1974.
“Vietnam strongly protests, urging China to investigate and seriously deal with the wrongful and inhumane act, and compensate Vietnamese fishermen for their loss,” foreign ministry spokesman Luong Thanh Nghi said.
A formal complaint had been lodged with the Chinese embassy in Hanoi, the statement released late on Monday said.
Earlier this month, two Vietnamese fishing boats were chased out of disputed waters by Chinese marine surveillance ships, local reports said. Vietnamese officials have also reported increased patrolling by China in recent months.
But the use of firearms, if confirmed, points to a more forceful approach from Beijing in protecting what it calls China’s sovereign waters.
There has so far been no comment from Beijing on the issue.
In recent years tensions over territorial claims have been rising in the South China Sea, amid a more assertive stance from China.
China claims a U-shaped swathe of the sea that extends well into what UNCLOS (UN Convention on the Law of the Sea) recognizes as the 200-mile-from-shore Exclusive Economic Zones of other claimants.
As well as Vietnam, the Philippines, Brunei, Malaysia and Taiwan have overlapping claims with China.
Last year, the Philippines and China engaged in a lengthy stand-off over another disputed area, the Scarborough shoal, in a spat that left diplomatic ties very strained.
Both the Philippines and Vietnam have sought to raise the issue through the ASEAN regional bloc, but claim Chinese pressure has forced the topic off the agenda.