The two countries signed a land border agreement in 1999, but it took them nine years to demarcate the 840-mile (1,350-kilometre) frontier.

The demarcation is 'an event of great historic significance in Vietnam-China relations', Vietnam News Agency quoted a joint statement issued on Wednesday at the end of their four-day meeting in Hanoi as saying.

The two sides, represented by Vietnamese Vice-Foreign Minister Vu Dung and his Chinese counterpart Wu Dawei, pledged to build a border of 'peace, friendship and long-term stability', it said.

China backed the Vietnamese communists during the Vietnam War, but sent troops to invade Vietnam in early 1979 for ousting Cambodia's Khmer Rouge, which was backed by Beijing.

The two countries normalised relations in 1991 and have since maintained annual high-level visits.

The two sides, however, did not resolve their hot dispute over the Spratlys islands, the largely uninhabited islands and surrounding waters are believed to have large oil and natural gas reserves. They straddle busy sea lanes and are rich fishing grounds.

Taiwan, the Philippines, Malaysia and Brunei also claim sovereignty over all or some of the Spratlys.

The dispute sparked rare anti-China street protest in Vietnam late last year. -- AP