Kenyan police have fired tear gas and water cannons to disperse protesters as thousands took to the streets to mark the first anniversary of anti-government demonstrations that left dozens dead.

Sixteen people died during nationwide anti-government protests in Kenya on Wednesday, most of them killed by police, the head of Amnesty Kenya said, a year after deadly demonstrations against a tax bill culminated in the storming of parliament.

Human rights groups say at least 16 people have been killed and over 400 injured during nationwide protests in Kenya.