Hillary Clinton Wednesday vowed to do more to help Laos clear millions of unexploded US bombs left from the Vietnam War, after a poignant plea from a young man who lost his hands and sight.

Touring a centre in Vientiane which helps victims who have been injured by the decades-old unexploded ordnance, the US secretary of state was clearly moved when she was introduced to softly-spoken Phongsavath Souliylath.

Clutching a long, thin walking cane between the withered stumps of his arms, the young man told how his life changed forever on his 16th birthday some four years ago.

Strolling in his home village in northern Laos, his friend picked up a piece of a cluster bomb and gave it to him. It blew up in his face, robbing him of his eyesight and blowing off his hands.

He was eventually taken to the Cooperative Orthotic and Prosthetic Enterprise (COPE) in the capital city, which helps people by fitting them with false limbs and providing occupational therapy so they can learn to use them.

"I would like to see all governments clear the bombs together and help the survivors. So many survivors without help. Their life is very, very hard," the man, who now volunteers at the centre, told Clinton in halting English as she patted him on the shoulder.

"I think you are absolutely right. We have to do more and that's one of the reasons I wanted to come today so that we can tell more people about the work we should be doing together," Clinton replied.

With an extraordinary lack of rancour, Phongsavath added: "I wish you and all the people, and the American government.. to have a good health and that all your good dreams come true."

Clinton, clearly struck by his words, said: "That is so wonderful and I want to say the same back to you," also offering him "blessings".

His story is repeated all too often in this Southeast Asian nation where some 80 million unexploded cluster bombs are still scattered in the fields and rice paddies, or deep in the jungles more than three decades after the war.

At least 100 people a year, almost half of them children, are killed or maimed by the deadly, rusting bombs which lie buried in the soft, muddy countryside. In total 50,000 people have been killed by the explosives since the end of the war.

Per capita, Laos was the most heavily bombed country in the world. From 1964 until 1975 when the Vietnam War ended, some 580,000 US bombing runs were flown over Laos as the United States sought to cut off North Vietnamese supply routes.

"Because of the rains, some of the bombs have slipped under the ground," Khamcham Phetsouphan, marketing assistant at the COPE centre told AFP.

"This is a big problem, as most of the people in this country are farmers."

He explained how the resourceful Laotians -- in one of the poorest countries in Southeast Asia -- have turned to transforming scrap metal recycled from the bombs into everyday items.

Parts have been turned into cooking pots and candles, huge bomb husks are used as shiny boats to float on the rivers and rows of bombshells even stand as fences around children's play areas.

The United States has so far spent some $68 million to help Laos clear the ordnance and in 2012 will put up about $9 million more. Clinton said some 23,000 hectares had been made safe.

Calling her visit to the COPE centre "a painful reminder of the legacy of the Vietnam War era", she told a gathering of US embassy staff and their families that efforts had to be made to make the country safe for its people.

Back at the COPE centre, which has a sign above the door spelling out its name in false limbs, one simple black and white drawing on a wall of postcards designed by children captured Clinton's haunting visit.

"Buy a leg, $75," it read, next to drawing of a shapely woman's leg in a high heel.