An international human rights organization is calling for Kenya's government to provide information on dozens of people who have been reported missing during a security operation against a militia in the country's west.  As Derek Kilner reports from Nairobi, Human Rights Watch is also asking western governments to suspend military and police aid to Kenya until there is an investigation into the conduct of the security forces.

In a new report, Human Rights Watch accuses both Kenyan security forces and the Sabaot Land Defense Force militia of war crimes.  

The report charges Kenya's police with widespread torture and several disappearances in an operation against the SLDF militia earlier this year in the Mount Elgon region of western Kenya.

Human Rights Watch lead researcher for the report, Ben Rawlence, said the government appears to have backed away from torture and mass arrests in recent months, and concedes that most of Mount Elgon's residents are happy that the military has intervened against the SLDF, which is accused of killing about 600 people, and of torturing and raping many more, in a conflict over land distribution that began in mid-2006.

But he said Kenya's security forces must be held accountable for their actions during March and April.

"Such a strategy is very concerning," Rawlence said. "The allegations need to be investigated. People need to be brought to book, so that the security forces learn that this is not an acceptable way of dealing with an insurgency. However heinous and appalling the atrocities of the SLDF, the military, the police, and the security forces in general must respond to security crises in accordance with the law."

Human Rights Watch called on donor governments, particularly Britain and the United States, to withhold aid for Kenya's police and military until there is an independent investigation into the conduct of security forces in Mount Elgon.

Kenyan police spokesman Eric Kiraithe said he had not seen the report, but rejected its accusations.

"We are very, very, very confident that, whereas you cannot rule out like in any other operation anywhere in the world, that there is a possibility one or two personnel whether from the military or the police might have abused human rights, there is nothing like systematic torture," Kiraithe said.  "There is nothing like torture as a policy, or torture as a major tool of carrying out the operation. There is nothing like that."

Mr. Kiraithe questioned the reliability of many of the sources that the report's author, Mr. Rawlence has drawn on, saying many people had fabricated stories of torture by the police or military.

Since the military operation began in March, Kenyan human rights groups have drawn attention to reports of police and military misconduct.  Hassan Omar, is a commissioner for the government-funded Kenya National Commission on Human Rights, which released its own report on the subject earlier this year.

"Since we released our report a couple of months ago, there has been a strategy of denial from the security apparatus," Omar said.  "The thing is, they cannot get away with this.  These are not the '60s, these are not the '70s, these are not the '80s, this is a new season for Kenya, and everything needs accountability."

Mr. Kiraithe said the police would be releasing a report of their own investigation into the operation in Mount Elgon this week.  Kenyan groups have criticized the police for delaying the release of the report.