(Updates with government reaction, paragraphs 4-5) By Andrew Cawthorne NAIROBI, Feb 25 (Reuters) - The United Nations investigator into extra-judicial killings said on Wednesday that Kenya's police chief and attorney-general should be fired because of hundreds of alleged murders by security forces. "Kenyan police are a law unto themselves and they kill often and with impunity," Philip Alston, U.N. rapporteur on extrajudicial, summary and arbitrary executions, said at the end of a 10-day visit to the east African nation. The Australian official backed accusations that security forces have killed 500 suspected members of the outlawed Mungiki crime gang, 400 political demonstrators during a post-election crisis last year, and 200 suspected rebels from the remote western region of Mount Elgon. Kenya's coalition government, facing criticism from foreign donors and the public for allowing and even fanning both corruption and rights abuses, rejected Alston's conclusions. The police and military deny all the allegations. "The government finds it inconceivable that someone who has been in the country for less than 10 days can purport to have conducted comprehensive and accurate research on such a serious matter," a government statement said. Alston's report, laced with sarcastic references to the authorities' failure to respond properly to the accusations, was one of the strongest indictments of impunity in Kenya. "There is zero internal accountability -- the police who kill are the very same police who investigate police killings," Alston told a news conference, saying only the rare few caught committing abuses on camera were ever prosecuted. He accused police commissioner Hussein Ali of "stonewalling" and responding to questions such as "how many policemen are there in Kenya?" with the phrase "not immediately available". "IMPUNITY" "Any serious commitment to ending the impunity that currently reigns in relation to the widespread and systematic killings by the police should begin with the immediate dismissal of the police commissioner," Alson said. Alston was scathing about attorney-general Amos Wako: "Mr Wako is the embodiment in Kenya of the phenomenon of impunity." Alston's report came amid a furore over a videotape and statements from a policeman that he witnessed a police death squad strangling, shooting and hacking to death 58 people in a crackdown on the Mungiki. The policeman was later murdered. The government-funded Kenya National Commission on Human Rights, which released video clips and statements by former police squad driver Bernard Kiriinya, also urged the police chief to step down. Kiriinya -- whom the rights group says was shot dead in a Nairobi street just outside a safe house last year, several months after giving his testimony -- described in detail what he says was the killing of Mungiki suspects. The group, known for its macabre tactics including beheading and skinning victims, runs extortion rackets in central Kenya. In his testimony, Kiriinya described police spraying victims with bullets as they laid face down, strangling them with rope, and hacking them to death with machetes. Victims were often disfigured afterwards to prevent recognition, then dumped in remote bush or woodland, he said. The police squad sometimes received money, and even compliments from the top, for their work, Kiriinya added. A provincial police officer "told us that the Commissioner of Police Major General Hussein Mohammed Ali had sent his compliments for 'kazi mzuri," he said of one killing, using the Swahili for 'good work'. Police spokesmen dismissed the accusations as false, and said Kiriinya had been a bitter and disaffected officer. (Editing by Matthew Tostevin)
REFILE - CLARIFYING CAPTION INFORMATION An elderly man wipes tears from his eyes during a mass funeral for 89 people killed in a fire a fortnight ago in Molo town, about ...
