Amnesty International says Lao troops are preventing Hmong rebel families from obtaining food. It says starvation as a tool of war violates the Geneva Convention - ratified by Laos.
The London-based human rights group says it is "gravely" concerned with the deteriorating situation of thousands of Hmong rebel families caught in the armed struggle with the Laos military in heavy jungle areas of the country.
Daniel Alberman, from Amnesty International's London office, says the situation is grave. He adds:
"The reports we're getting are really of a dire situation. Basically the groups who are hiding out in the jungle, they survive on foraging for food, for wild cassava and for tree roots. In the past, they've grown rice, but to grow rice, you have to clear jungle, and if you clear jungle, it's easy to spot where you are from helicopters."
Mr. Alberman says the Hmong rely on being able to move freely to eat, and the military is preventing this. He says:
"Basically it seems to be a sort of situation of attrition and the death rates that are being reported to us are truly horrendous, especially for the most vulnerable, which in this case is mostly children."
But Amnesty also criticized the Hmong rebels. It called on the group to stop indiscriminate attacks on and bombings of civilian targets and to end using children as soldiers.
The Hmong rebels are thought to be behind several deadly bombings and a number of attacks on buses running along the country's main highway.
The Hmong have been fighting in Laos since the 1970s when the U-S quietly backed them in a secret war against communism.
The communist Lao government does not recognize the Hmong rebellion and will only refer to the group as "bandits."