Vietnam says it has evidence that Chinese sailors detained and beat several Vietnamese fishermen last month off disputed islands in the South China Sea.

Hanoi's foreign ministry says the fishermen were stopped near the Paracel Islands on August 15. It said Chinese sailors on speedboats vandalized the Vietnamese boats, took away fishing equipment and beat some of the fishermen.

The deputy head of the Vietnam's Fisheries Association, Vo Van Trac, says in an interview with VOA's Vietnamese service that Hanoi has evidence to back up its accusations.

"Regarding China’s acts of assaulting Vietnamese fishermen and confiscating their properties, local authorities [of Quang Ngai province] has submitted a report to the ministry with supporting evidence of course. China says they didn’t attack Vietnamese fishermen, that’s just their words, they have to provide with evidence as well and we do have to check on that. Our accusations are always evidence-based," said Van Trac.

China's foreign ministry on Wednesday rejected the claims as "absolutely false." It claims the fishermen entered China's waters, and that the Chinese sailors detained the Vietnamese boat along with explosives used to illegally catch fish.

Phan Huy Hoang, an official in Quang Ngai province where the fishermen are based, says Vietnamese fishermen are regularly briefed on laws to curb illegal activities.

“We’ve been educating fishermen to protect natural resources and not to violate rules while fishing.  We’ve been regularly educating and propagandizing such things according to government rules," said Hoang.

Vietnam has demanded that China fully investigate the incident and punish the sailors responsible.

Vietnam and China are in a long-running dispute over the Paracel Islands, which are controlled by Beijing. In May, the dispute worsened when China deployed a state-run oil rig near the islands. Beijing later removed the rig, although ties were severely damaged.

China claims almost all of the South China Sea, putting it at odds with Vietnam, the Philippines, Brunei, Malaysia and Taiwan.