Riot police in Malaysia have fired tear gas and used water cannon on an estimated 25,000 protesters who converged on the centre of the capital, Kuala Lumpur.
They marched on a square in the city calling for changes to the electoral system.
They believe the current arrangements will benefit Prime Minister Najib Razak's long-ruling coalition in forthcoming elections.
The rally is one of the largest in the country in the past decade.