However police spokesman Bruno Shioso told the BBC that investigations had yet to reveal those responsible or the motive behind the killings.

There seems be some discrepancy over the numbers.

On Tuesday, activists went to the Yala Sub-County Hospital, about 40km (24 miles) north-west of the lakeside city of Kisumu, and said they counted 20 bodies recovered from River Yala which had been unclaimed.

As the hospital only keeps unclaimed bodies for 90 days, they must have been recovered over the last three months.

BBC journalists have since seen two more bodies in the river.

But in a statement on Wednesday, the National Police Service said it had cases of only 19 bodies being reported over a period of two years.

A diver who says he has been helping retrieve the corpses for the last six months believes there could be many more bodies in the river.

Families missing their loved ones have started reporting to the local police headquarters hoping to identify the bodies, some of which are badly decomposed.

The police say a special forensics team has been sent to Yala to speed up the identification of the victims.

Anxious Kenyans are demanding answers, amid allegations that most of the bodies recovered from the river had shown signs of torture.