Kenya's under-fire police on Sunday pledged a "transparent" investigation into the shocking discovery of eight mutilated female bodies dumped in a Nairobi garbage site.

But tensions were running high at the crime scene in the Mukuru slum area in the south of the Kenyan capital, as police briefly fired tear gas to disperse a crowd of angry residents, an AFP journalist said.

Police chiefs said they were pursuing possible links to cults, serial killers or rogue medical practitioners in their investigation into the macabre saga, which has horrified and angered the nation.

The mutilated and dismembered bodies, trussed up in plastic bags, were hauled out of a sea of floating rubbish in an abandoned quarry in Mukuru.

The discoveries have thrown another spotlight on Kenyan police and added more pressure on President William Ruto, who is struggling to contain a crisis over widespread anti-government protests that saw dozens of demonstrators killed.

Acting national police chief Douglas Kanja said six corpses were found in Mukuru on Friday and more body parts were retrieved on Saturday, with preliminary investigations revealing that all were female.

"They were severely dismembered in different states of decomposition and left in sacks," Kanja told a press conference, describing it as a "heinous act".

He said police were committed to conducting "transparent, thorough and swift investigations" adding that they aimed to wrap up their inquiries in 21 days.

Kanja, who was appointed only on Friday amid the fallout over last month's protest bloodshed, also said that all officers at the police station located near the quarry had been transferred.

 Police watchdog probe 

 Kenya's police watchdog, the Independent Police Oversight Authority (IPOA), on Friday had said it was investigating whether there was any police involvement in the dumped bodies, noting that the dumpsite was just 100 metres (yards) from the police post.

The IPOA also said it was looking into claims of abductions of demonstrators who went missing after last month's protests.

But it did not make any link to those missing and the dumped bodies.

The AFP journalist said in the absence of a police search on Sunday, volunteers were combing through the vast piles of rubbish in search of more victims.

Trouble briefly erupted when locals tried to take a bag they had hauled out of quarry to the police station, but were met with volleys of tear gas, the journalist said.

Mohamed Amin, the head of the Directorate of Criminal Investigations, said the ages of the victims ranged from 18 to 30 and that all had been killed and butchered in the same manner.

"Are we dealing with a cult that is associated with criminal activities, are we dealing with serial killers?" he said at the press briefing alongside Kanja.

"We even could be dealing with rogue medical practitioners."

 Cult massacre 

 Kenya was left reeling last year by the discovery of mass graves in a forest near the Indian Ocean coast containing the bodies of more than 400 members of a doomsday sect, one of the world's worst cult-related massacres.

On Monday, self-proclaimed pastor Paul Nthenge Mackenzie went on trial on terrorism charges, along with 94 co-defendants, over the deaths, accused of inciting his followers to starve themselves to death in order to meet Jesus.

He and the other accused also face charges of murder, manslaughter and child cruelty in separate cases over what has been dubbed the "Shakahola forest massacre".

The country's law enforcement services are already under scrutiny over the protest deaths, with rights groups accusing police of using excessive force.

Kanja took up his post only this week after national police chief Japhet Koome resigned in the face of public fury over the alleged police brutality.

A total of 39 people were killed and more than 630 injured during the unrest, Kenya's national rights commission said earlier this month.

Kenyan police are often accused by rights groups of using excessive force and carrying out unlawful killings or running hit squads, but few have faced justice.