Two Kenyan campaigners against extra-judicial police killings have been shot dead hours after the government called them a front for a notorious crime gang.
"We are in shock. These two were well-known within the human rights community," Florence Jaoko, chairwoman of state-funded Kenya National Commission on Human Rights, told Reuters.
"We want an investigation. Nothing warrants their deaths."
Unidentified gunmen killed Oscar Foundation director Kamau Kingara and programmes coordinator Paul Oulo after blocking their car on a central Nairobi street following a day of protests yesterday by the Mungiki gang in central Kenya.
Gathering protests against alleged police killings have added to widespread disillusionment with the poor record of a year-old coalition government formed to end Kenya's bloody post-election crisis a year ago.
The Oscar Foundation officials had mobilised protests against what they said was the illegal killing of 1,721 young people and the disappearance of 6,542 others suspected by the police of being Mungiki members or sympathisers.
Other rights groups, and a UN special investigator had put the number killed in a 2007 crackdown at around 500.
Five hours before the killing of Kingara and Oulo last night, government spokesman Alfred Mutua had called the Oscar Foundation a "front" for Mungiki.
The gang, which draws support from Kenya's young and jobless, is known for its extortion rackets and gruesome killings, including beheadings. It claims to be the successor of Kenya's anti-colonial Mau Mau rebel movement.
Civil society activists blamed authorities for the murders but police denied involvement.
"This is a very unfortunate matter, given the fact that there was a (UN) report on extra-judicial killings just last week. So you would expect some people to say we can be involved in this," police spokesman Charles Owino said.
"But it would be too cheap for the police to get involved with people involved in protecting rights. We have no reason whatsoever to kill people, even if they are against us. We consider it either rivalry or thuggery, and we are committed to bringing the perpetrators to book."
United Nations special rapporteur on extrajudicial executions Philip Alston, who met both the dead men during a visit to Kenya in late February, called for a foreign-led probe into their killings.
"The shocking assassination in Nairobi of two prominent Kenyan human rights defenders must be independently investigated," Alston said in a statement from New York.
"It is imperative, if the Kenyan police are to be exonerated, for an independent team to be called from somewhere like Scotland Yard or the South African Police to investigate."
Alston last week called for the dismissal of police chief Hussein Ali and resignation of Attorney-General Amos Wako after backing allegations of hundreds of killings by security forces.
Kenyan media and some rights activists said an eyewitness to yesterday's killings was also wounded in the shooting, and was taken away by men at the scene. Students protested nearby afterwards, and media said one was killed.
Government spokesman Mutua was not answering his phone today.