Fears mounted of a bloody showdown between supporters and opponents of Egypt\'s Islamist President Mohamed Morsi on Friday after one activist was killed in the latest violence to cloud the Arab world\'s most populous democracy. Islamist groups called on their supporters to camp out indefinitely in a Cairo square two days before a planned protest by the mainly secular opposition to demand Morsi\'s resignation just a year after he took office. The Islamists charge that their opponents are undermining Egypt\'s fledgling democracy less than two and a half years after the popular uprising that overthrew veteran strongman Hosni Mubarak. Their opponents say that the president has reneged on his promise to rule for all Egyptians and has failed to deliver on the uprising\'s aspirations for freedom and social justice. The overnight violence erupted in the eastern part of the Nile Delta, north of the capital, Morsi\'s own home province. Rival demonstrators clashed outside offices of the Muslim Brotherhood\'s political arm, the Freedom and Justice Party, on whose platform the president won election last year. The FJP said on its website that one of its supporters was killed. Thirty people were also wounded, the health ministry said. The Muslim Brotherhood and its Islamist allies called on their supporters to mass outside the Rabaa al-Adawiya mosque in Cairo\'s Nasr City district under the slogan \"legitimacy is a red line\". The Islamists charge that opposition demands for Morsi\'s departure, barely a year after he won Egypt\'s first freely contested election, amount to an attempted coup and accuse the opposition of sympathy with the ousted Mubarak. The president himself warned in a televised speech on Wednesday that the growing polarisation between his fans and foes threatens to \"paralyse\" Egypt. He pledged to consider constitutional reforms and appealed to the opposition to join talks. It was his latest attempt to strike up a dialogue between political factions in a country deeply split between his Islamist allies and an opposition of leftists, liberals, Christians and some Muslim groups. But late on Thursday, the opposition National Salvation Front coalition rejected his offer of talks and renewed its call for a snap election to replace him. Since taking office a year ago, Morsi has squared off against the judiciary, media, police and even artists. However, he has admitted to failings and has vowed to correct them. \"I have made many mistakes, there is no question. Mistakes can happen, but they need to be corrected,\" he said. He warned the media against abusing the freedoms they won from the 2011 uprising. Judges imposed a ban on foreign travel on Thursday on the owner of a private television channel that hosts a popular satire show. Mohammed al-Amin, owner of CBC television, faces charges of tax evasion, and Morsi singled him out by name in Wednesday\'s speech. The army, which oversaw the transition from Mubarak\'s autocratic rule but has been on the sidelines since Morsi\'s election, warned it would intervene if violence breaks out. It has brought in reinforcements to key cities, security officials said. In Cairo, residents are withdrawing cash and stocking up on food, and many companies have said they will close on Sunday, the first day of the working week in Egypt. Fuel shortages have seen drivers queueing outside petrol stations through the night, bringing parts of the capital to a standstill.