NAIROBI - Ugandan troops have tortured and killed civilians in operations against cattle rustlers in a remote northeast region, a human rights group said on Tuesday.

Warriors toting assault rifles have long plagued Karamoja, an impoverished semi-arid area bordering Kenya and south Sudan that is notorious for looting, ambushes and livestock raids.

"The Ugandan government has every right to get guns out of the hands of ordinary citizens, but its soldiers must still obey the law," Elizabeth Evenson, a Human Rights Watch researcher, said in a report released by the New York-based advocacy group.

Human Rights Watch said its publication was based on some 50 eyewitness accounts of Ugandan military operations in Karamoja in the last year, plus visits to the sites of six operations.

It said witnesses described troops shooting dead three children, severely beating men to force them to uncover hidden weapons, and using armoured cars to flatten homesteads.

"Ugandan soldiers have tortured and unlawfully killed civilians during law enforcement operations in the Karamoja region," the report said.

Ugandan officials were not immediately available to comment on the report, but have in the past denied similar allegations.

In April, the U.N. High Commissioner for Human Rights, Louise Arbour, accused Uganda of using indiscriminate and excessive force causing the death of civilians in Karamoja.

But last week, her office said that since then there had been a "marked reduction" in human rights violations, road ambushes and illegal firearms in Uganda's poorest region.

It said the Ugandan military had recovered more than 1,500 weapons in "cordon and search" operations since the start of the year and had returned 5,344 stolen cows to their owners.

But some Ugandan soldiers still violated human rights with killings, torture and the use of excessive force, it said, echoing Arbour's calls for thorough and timely investigations.

Human Rights Watch said government efforts to redress and prevent such abuses had so far been promising, but insufficient.

"If these abuses continue to go unacknowledged and unpunished, future abuses are inevitable," Evenson said.

"As host of the Commonwealth summit (on Nov. 23-25), Uganda should demonstrate its commitment to the Commonwealth values of human rights and the rule of law by ensuring its soldiers respect human rights during operations in Karamoja."