Supporters of one of the two rival presidents in Ivory Coast say they intend to take to the streets again, a day after gun battles in the main city of Abidjan left at least 20 dead. On Thursday Alassane Ouattara's backers tried to march on the headquarters of state TV, but clashed with troops loyal to his rival, Laurent Gbagbo. Each man claims to have won last month's presidential election. The UN Security Council has expressed deep concern over the violence. It warned that all sides would be held accountable under international law for any attacks against civilians, as fears rose the country could slide back towards civil war. >b>Ceasefire line Mr Ouattara has been staying at a hotel in Abidjan since the disputed polls. His supporters, including his nominated prime minister Guillaume Soro, were trying to leave the hotel compound and march to the TV station on Thursday when fighting broke out. A spokeswoman for Mr Gbagbo said 10 protesters and 10 members of the security forces had died. Officials from Mr Ouattara's camp put the number of dead at 30 or more. Most of the violence was reported in Abidjan, but on Thursday afternoon it appeared to be spreading, with reports emerging of unrest elsewhere. Former rebels from the New Forces fighters - who back Mr Ouattara - apparently tried to storm positions held by the military near the town of Tiebissou, just south of the ceasefire line agreed in 2003 to end the country's year-long civil war. The sides exchanged fire and civilians fled the town, reports say, but there were no confirmed casualties. The trouble stems from last month's run-off election, which the Electoral Commission said Mr Ouattara won by 54% to 46%. Mr Gbagbo refused to admit defeat, and the Constitutional Council then annulled some results from the north and declared Mr Gbagbo the winner. The UN has about 10,000 peacekeepers in Ivory Coast; it has made it clear it wants Mr Gbagbo to stand down. In Washington, State Department spokesman PJ Crowley said a combined delegation from the African Union and the Economic Community of West African States (Ecowas) would be in Abidjan soon "to continue to encourage President Gbagbo to step aside". Source: BBC