The pitiful encounter in the depths of the Lao jungle changed the life of the photographer who documented it. It should also have changed the lives of the people he photographed. When Philip Blenkinsop met this group of Hmong in January 2003, they were in hiding, desperate, trapped in an inconceivably terrible existence. They threw themselves on their knees when they saw him, believing rescue had come at last. It hadn’t.

The Hmong migrated to Laos from China in the 19th century – to escape persecution, ironically. In the second world war they sided with the French against the Japanese. Thirty years ago they were trained by the CIA to fight with the Americans in Vietnam, believing in their promises of an independent homeland when (not if) the war was won. As many as 40,000 Hmong were killed in the fighting. Even at the time, their messy part of the conflict, in officially neutral Laos, was known as the “secret war”. When the US bailed out and the last few Americans were airlifted to safety, the Hmong were abandoned, a secret nobody wanted to share.

About 200,000 Hmong managed to escape to Thailand, and from there many went to the US (where they were often looked down on as scroungers). The rest were left to defend themselves with a few old guns against the Pathet Lao, a military force bent on their destruction. In 1977 a communist newspaper promised the party would hunt down the “American collaborators” and their families “to the last root”.

Blenkinsop’s powerful images were published in this magazine on October 12, 2003. They have won 11 international awards and have been exhibited all over the world, most recently at the National Library of France in Paris. It is difficult to remain unmoved. Blenkinsop believed that once people learnt of the Hmong’s dire fate, international pressure would result in their being granted safety. It’s three years later. There was no such international pressure. Human-rights groups such as Amnesty International continue to petition Laos to allow in UN monitors and humanitarian-relief workers, to no avail. The Hmong, the last casualties of a war that officially ended in 1975, are still dying.

Not just dying: they are being wiped out. Hunted, shot, bombed, blown up by landmines, starved to death – by the Lao military, possibly with the help of the Vietnamese. Why? They are officially traitors – and, by grotesque extension, so are their children and grandchildren.

Blenkinsop, an Australian photographer based in Bangkok, remains haunted by the few days he spent with the Hmong in January 2003. “Whenever I look at that image of them kneeling, the sound of their grieving washes over me. It will be with me to my grave,” he says. He had spent four days trekking through bamboo forest and wading across rivers with a local guide to arrive at the Hmong’s secret location. The group he met, in the Xaysomboune zone, numbered around 800 men, women and children; in total there were an estimated 12,000 former fighters and their descendants across the country. Nobody knows how many are still alive.

To avoid Lao forces, the group were constantly on the move, and they survived largely on tree roots. “At night it was bitterly cold,” recalls Blenkinsop. “The fire would die after about 30 minutes and I’d soon wake freezing and spend half an hour rebuilding it and warming myself through. I didn’t sleep more than 40 minutes at a stretch in 10 days. The only meat we had on the walk in was venison from a deer that had tripped a booby trap and been ripped apart by shrapnel a week earlier. We cut pieces from it where it lay – flyblown, blue meat. My Hmong companions had no trouble with it at all, as it was a luxury for them, but it was hard not to gag.”

He arrived near their makeshift camp in January 2003. Hundreds of people were standing in silence in a clearing. “As we approached, each and every man, woman and child fell to their knees, crying.” There were tiny children, their bellies distended from starvation. Older men with shrapnel injuries. Younger men with wounds that refused to heal. All pouring out their sorrow and loss to the person they thought was their American saviour. “How could you have abandoned us for so long?” “Look how we are made to live like animals.” “We are hunted like dogs.”

Certain individuals he will never forget. “I could always tell when Bang Yang was nearby. An orphan, a widow and a single mother at the age of 14 (her 15-year-old husband had been shot and killed before her child was born), she didn’t stop crying, mourning her losses, for the entire duration of my stay. Whenever she was close, I could pinpoint her location from the sound of her sobs.”

In the past few years, hundreds, perhaps thousands of Hmong have fled Laos; many are now in refugee camps in Thailand, from where they are sometimes forced back to Laos and likely death. Amnesty International reports that a group of 27 Hmong, 22 of them children, mostly girls aged between 12 and 16, were arrested in Thailand while they were visiting a church last November and deported; they are now in prison and are believed to be being treated badly, possibly tortured. The Lao authorities deny responsibility, but “Disturbing reports of repression, arbitrary detention and violent attacks continue to emerge from the Lao jungle,” says Kate Allen, Amnesty’s UK director.I raised the matter with Soutsakhone Pathammavong, the Lao ambassador in Paris. His reply was to deny that any Hmong were being killed by his government’s army. He began: “Please be aware that Lao PDR is in peace since the Lao People’s Democratic Republic had been founded in 1975. Since then, the Government of Lao PDR had been implementing a policy of Peace, Independence, Unity and Prosperity where all the 49 Ethnics groups [sic] which formed the Lao National Community live in peace, solidarity, unity and have their rights guaranteed by the following articles of our Constitution.

“Article 1. The Lao People’s Democratic Republic is an independent country with sovereignty and territorial integrity covering both territorial waters and airspace. It is a unified country belonging to all multi-ethnic people and is indivisible. Article 2. The state of the Lao People’s Democratic Republic is a People’s Democratic State. All powers are of the people, by the people and for the interests of the multi-ethnic people of all strata in society with the workers, farmers and intellectuals as key components. Article 3. The rights of the multi-ethnic people to be the masters of the country are exercised and ensured through the functioning of the political system with the Lao People’s Revolutionary Party as its leading nucleus. Article 22. Lao citizens irrespective of their sex, social status, education, faith and ethnic groups are all equal before the law.”

He went on: “The Hmong ethnic group is part and parcel of our population and therefore [benefits from] the same rights and duties as stipulated in our Constitution, like any other ethnic groups. As I mentioned that Lao PDR is in peace since 1975, there is no more war and armed conflict. Since there is no war obviously there is no rebel in Lao PDR neither from the Hmong group nor among any other ethnic groups.