Police have fired tear gas and water cannon at stone-throwing crowds protesting in central Nairobi.

Officers armed with batons confronted hundreds of protesters outside the offices of the Kenyan Independent Electoral and Boundaries Commission.

The protesters say the organisation responsible for monitoring elections is biased and should be scrapped.

Eyewitnesses say police fired tear gas and water cannons from trucks.

There are reports of protesters throwing stones at police, who retaliated with batons.

It is the third clash over the issue in the last month.

What are the protests about?

Next presidential and parlimentary votes are in 2017

Opposition disputed the 2013 result

Violence erupted after the 2007 vote

The protesters are supporters of the opposition.

Despite the use of undue force by police, our peaceful pickets shall continue every week until the IEBC is reformed. pic.twitter.com/GMPFgQ3Ej4 — Raila Odinga (@RailaOdinga) May 16, 2016

Leader Raila Odinga lost the 2013 election vote and unsuccessfully challenged the result in court.

He has accused the IEBC of bias and said its members should quit.

IEBC officials have dismissed the charge and say they will stay in their positions.