The massacre took place under the No Gun Ri railway bridge in the South Korean countryside, and the soldiers said that as many as 300 South Koreans could have been killed.

Like the conflict in Vietnam, Korea is a war that Americans would rather forget -- and since it ended in 1953, the group of former GIs have never spoken publicly about what they have described as the massacre of No Gun Ri.

Edward Daily still hears the cries of the dying

Many of the victims were women and children, who, in the desperate first weeks of the war, tried to flee the country.

The precise death toll will never be known.

The soldiers were ordered to shoot because of the fear that Communist North Koreans would try to penetrate American lines by hiding amongst the refugees.

"We simply annihilated them," said one former GI.

No official record

The Pentagon has said that it has found no evidence to substantiate the soldiers' stories and there is no mention of any such massacre in the official army record.

The BBC's Stephen Sackur: "Old wounds have been reopened."

Victims of the shootings and their relatives have long sought compensation from the South Korean authorities. But last year, the government's compensation committee rejected their claim, saying that a five-year statute of limitations expired long ago.

The campaigners have always contended that the events of July 1950 were three days of unprovoked carnage. The accounts of the GIs who were there would appear to support that view.

Edward L Daily, who went into Korea as a corporal and came out a lieutenant, came under pressure from his former comrades not to write about No Gun Ri, when he first raised the idea in the 1980s.

"You try to put things in the back of your mind because life goes on," he said. "But as you get older, you're not as active as you were and you begin to think more about these things again."

He was pleased to tell a story that has gone untold for 49 years.

Another former GI, Norman Tinkler, said he was driven to speak by his conscience. "You've got to pay for your deeds sooner or later," he said.

Remembering the tragedy

Survivors also have vivid memories. Many had already come under attack from the air and were taking refuge under the arches of the bridge when American soldiers opened fire with machine guns.

Min Young-ok and her son were both victims

Yang Hae-sook, who was 12 at the time of the massacre in July 1950, said she thought she was safe under the bridge.

"Then the shooting came. Bullets ricocheted off the concrete and hit the people like popcorn in a frying pan. Mother wrapped me with a quilt and hugged me."

"It was shooting from both sides. When there was shooting coming from one side, we rushed to the other side."

Yang Hae-sook lost several relatives, including two brothers.

Not all American veterans want to remember the experience. Some objected to the investigation conducted by reporters from the Associated Press news agency.