International organisations appealed for calm on the eve of a presidential election in Democratic Republic of Congo already tainted by deadly street clashes and a showdown between security forces and the main opposition candidate. The European Union and the United Nations called for restraint after at least three people were killed in clashes on Saturday, the last day of campaigning, putting in doubt the central African state’s ability to ensure a representative vote in its second post-war presidential contest on Nov. 28. “The security forces should refrain from any acts that could heighten tensions and create any difficulties on the eve of elections,” Mounoubai Madnodje, spokesman for the U.N. peacekeeping mission, said. The EU observer mission accused the Congolese police of denying President Joseph Kabila’s main rival, Etienne Tshisekedi, his right to campaign in the capital after he was blocked at the airport on Saturday.