Sri Lanka last night scored a major propaganda coup when the UN human rights council praised its victory over the Tamil Tigers and refused calls to investigate allegations of war crimes by both sides in the final chapter of a bloody 25-year conflict.

In a shock move, which dismayed western nations critical of Sri Lanka's approach, the island's diplomats succeeded in lobbying enough of its south Asian allies to pass a resolution describing the conflict as a "domestic matter that doesn't warrant outside interference".

The Geneva council session, called because of alarm over the high number of civilian casualties as well as the island's treatment of displaced Tamil civilians, also condemned the Tamil Tigers for using ordinary people as human shields.

In another controversial development, it supported the Sri Lankan government's decision to provide aid groups only with "access as may be appropriate" to refugee camps.

The Sri Lankan government denies it was responsible for the death of even one of the 7,000 civilians the UN estimates were killed in the first four months of the year.

Sri Lanka's human rights minister, Mahinda Samarasinghe, said: "This is a strong endorsement of our president's efforts to rout terrorism, and the successful handling of the world's biggest hostage crisis.

"This is a clear message that the international community is behind Sri Lanka."

Amnesty International described the vote as "extremely disappointing" and a "low point for the human rights council", with a spokesperson saying: "It abandons hundreds of thousands of people in Sri Lanka to cynical political considerations."

European countries, along with Canada, Chile and Mexico had backed an investigation into allegations that the Tigers prevented civilians from leaving the densely populated conflict zone, and that government forces used heavy artillery on the area and killed rebels trying to surrender.

They also urged Sri Lanka to open up refugee camps fully to international aid agencies.

The Red Cross and other groups say they remain barred from visiting some camps despite repeated requests for access.

Aid groups want to check on conditions for the hundreds of thousands of civilians displaced by the fighting.

The Red Cross – which usually refrains from publicly criticising governments – complained Sri Lanka had denied it access to the war zone during the final weeks of the conflict.

Sri Lanka's ambassador in Geneva said European nations had failed with a "punitive and mean-spirited agenda" against his country.

"This was a lesson that a handful of countries which depict themselves as the international community do not really constitute the majority," Dayan Jayatilleka told the Associated Press.

"The vast mass of humanity are in support of Sri Lanka."

The UN human rights council has no enforcement power, but countries are generally keen to avoid criticism and the negative attention its resolutions bring.