Supporters of an unsuccessful presidential candidate clashed with security forces and set fire to a police dormitory and vehicles in the Indonesian capital on Wednesday after the release of official election results.
National Police spokesman Dedi Prasetyo said protests turned violent late Tuesday and continued through the night. He said Wednesday that dozens of people were detained.
KompasTV showed protesters throwing rocks, a paramilitary police dormitory on fire, and hundreds of riot police in a central neighbourhood of the city.
Indonesia's Election Commission on Tuesday said President Joko Widodo had won a second term with 55.5 per cent of the vote in the April 17 election.
His opponent, former general Prabowo Subianto, has refused to accept the results and declared himself the winner. His campaign plans to challenge the election in the Constitutional Court. They allege massive fraud but have provided no credible evidence.
Jakarta police spokesman Argo Yuwono said police used tear gas and water cannon against protesters who threw rocks, Molotov cocktails and burning projectiles.