A state-funded human rights body in Kenya on Wednesday produced what it is calling further evidence of widespread extrajudicial killings by Kenyan police. As Derek Kilner reports from Nairobi, the police have vigorously denied the accusations.

The Kenya National Commission on Human Rights and the national police are engaged in a dispute over a report released on Monday by the commission. The report charges the police with nearly 500 cases of extrajudicial killings earlier this year in a crackdown on the criminal Mungiki gang.

On Tuesday, Police Commissioner Hussein Ali accused the human rights commission of making accusations without evidence. In response, the commission on Wednesday held a news conference to draw attention to evidence supporting allegations of police misconduct.

At the conference, Commissioner Njonjo Mue ran through some examples in the report.

"We are not sure which part of the report we should highlight for the police commissioner as constituting evidence," said Njonjo Mue. "Should it be the part that shows that bodies of people shot through the head were left in the wild even after reports were made to the police? Or should it be the part that documents a surprising rise in the number of bodies dumped in mortuaries as soon as the crime crackdown on Mungiki was announced".

A senior official at the commission, Kamanda Mucheke, then presented a series of post-mortem reports conducted by doctors, including one about a victim who had been shot in the head.

"The cause of death was rear head injury due to double gunshots to the head," said Kamanda Mucheke. "These gunshots were fired at very close range. This amounts to an execution"

Police spokesman Eric Kiraithe says he has not heard the commission's latest presentation, but he disputes the claim that 500 victims have been identified

"The legitimacy of the figure 500 is seriously doubtful," said Eric Kiraithe. "I've looked at that report. I've not seen an appendix of the names. We have not seen the circumstances under which those people are said to have died. And that figure we believe is a fabrication."

The Mungiki gang was responsible for a violent crime wave earlier this year in Nairobi and other parts of central Kenya. The attacks have waned in recent months.

Kiraithe says the police deserve credit for an overall decline in violent crime in Kenya and particularly in Nairobi, which has been notorious for its high crime rate.