The accident happened on Tuesday off Khanh Hoa province as four fishermen looking for scrap metal collected a 105-millimetre shell from waters near a former US naval base, Nguyen Van Thanh, head of the local police department, said.

The shell exploded when the men tried to take it apart, killing two of them.

Harvesting leftover wartime material, including unexploded ordnance, to sell as scrap metal remains a common cottage industry in poor areas of Vietnam.

According to the Vietnam-based mine charity Renew, out of the 15 million tons of munitions dropped by the United States during the conflict, 10 per cent failed to detonate on impact.

The bulk of the unexploded ordnance remains in the central and southern regions of the country, particularly around the demilitarized zone that divided North and South Vietnam until the end of the war in 1975.

Vietnamese government figures show unexploded ordnance has killed more than 42,000 people and wounded some 62,000 since 1975.

Deutsche Presse Agentur - April 28, 2011