The survey was agreed during a visit by a US veterans' leader

The head of the Vietnam Veterans of America Foundation (VVAF) and a senior official from the Vietnamese Defence Ministry signed the agreement in Hanoi.

The war ended almost 30 years ago, but leftover explosive devices cause injuries on an almost daily basis.

The $6m project begins next month in the centre of the country.

The survey will be carried out by the VVAF and the Vietnamese military in the provinces of Quang Tri, Quang Binh and Ha Tinh.

It will then be expanded to other areas.

"It will benefit both the people of Vietnam and America, as it will support the restoration and rebuilding of a nation still coping three decades later with the legacy of the war," said VVAF president, Bobby Muller, in a statement in Hanoi.

Since the war ended in 1975, an estimated 38,000 people have been killed and 100,000 injured by land mines or other unexploded devices.

"Vietnam has the unfortunate distinction of being the country that has had more bombs dropped on it than any other country in history," said Mr Muller.

"An undeniable fact is that the United States dropped those bombs."

Celebration

The survey will involve compiling a database of victims and mapping the areas where unexploded bombs and mines remain.

The US military has said more than 15 million tonnes of bombs, mines, artillery shells and other devices were used during the Vietnam War.

Up to 10% are estimated to have failed to explode and scores of people are killed and injured each year as a result.

Most of the accidents happen while people are farming or trying to collect the munitions.

Many children have been killed or injured, unaware of the dangers.

After the agreement was signed, Mr Muller and the Deputy Minister of Defence, Senior Lt. Gen. Nguyen Huy Hieu, celebrated with champagne and swapped war stories.

Both men were injured in Qan Tri province during the war.