A controversial referendum on a new constitution in Egypt due to start Saturday looks set to further split the country after the opposition called for a \'no\' vote and imposed conditions that could yet result in its boycott. Egypt\'s powerful army called off a national \"unity\" meeting between President Mohamed Morsi and opposition leaders that was supposed to happen Wednesday because responses from both sides \"were not at the level wished for.\" The dialogue has been pushed back to an unspecified \"later date,\" according to a statement on the military\'s official Facebook page. Morsi has brushed aside all opposition demands to halt the referendum on the constitution, which was drafted by a panel dominated by his Islamist allies and rushed through under near-absolute powers he gave up only last weekend after big protests. But many judges are refusing to oversee the vote, forcing Morsi to order the plebiscite to be split over two days, on Saturday and a week later, on December 22, to meet voting rules. Saturday will see voters in 10 governorates called to polling stations, including in the two biggest cities of Cairo and Alexandria. On December 22 it will be the turn of Giza, Port Said, Luxor and 14 other regions. Egyptians abroad started early voting Wednesday in embassies abroad, the official MENA news agency reported. The president has ordered the army to secure state institutions, giving them police powers up to the results of the referendum. Three weeks of protests  including violent clashes between Morsi\'s supporters and opponents last week that killed eight people and wounded hundreds have failed to sway Morsi and his Muslim Brotherhood from holding the referendum. The opposition National Salvation Front on Wednesday finally responded by urging its supporters to vote \'no\' ,but also warning it could call a last-minute boycott if Morsi\'s government failed to meet tough conditions. \"We call to Egyptians to go to polling stations to refuse the proposed constitution and to vote no,\" the Front said in a statement read by a spokesman at a news conference. It demanded, though, that the referendum take place on a single day, and that judges and independent foreign monitors watch over it. Those conditions appeared nearly impossible for Morsi to meet, and made Saturday\'s vote unpredictable. Egyptian citizens were divided over the referendum. \"I\'m voting yes,\" said Mohammed Hassan, a 28-year-old Cairo resident. \"The Muslim Brotherhood is good. No one has given them a chance. They\'ve been in power for five months compared to 30 years for Mubarak,\" he said, referring to toppled leader Hosni Mubarak. Mohammed Ibrahim Sayyid, in his 40s and sipping coffee in a cafe, felt differently. \"We don\'t like what\'s happening. We don\'t want another Afghanistan because of the Muslim Brotherhood. We are a big, diverse country of 80 million people. There shouldn\'t be one party ruling,\" he said. Hamdi Imam, a street bookseller in his 50s, said: \"I\'m not going to vote because the constitution has blood on it... The Muslim Brotherhood will destroy the country.\" Michael Wahid Hanna, a political analyst at US think-tank The Century Foundation, told AFP that, given the Muslim Brotherhood\'s proven ability to mobilise grassroots support, the odds were good that the referendum would pass, although it was not \"an absolute certainty.\" If it did pass, \"it would be problematic for the future\" because it would ensnare all of Morsi\'s future decisions in political polarisation. \"If you overreach in this fashion, it will provoke a reaction and extend instability,\" Hanna said, warning of \"the spectre of violence\". The military has already said it fears the Arab world\'s most populous country is headed for a disastrous \"dark tunnel\" unless the two sides talk. It has warned it will not allow the situation to worsen. Troops and tanks are already deployed outside Morsi\'s palace in Cairo. The United States said there were \"real and legitimate questions\" about the referendum process and urged Egypt\'s army, which it gives $1.3 billion in aid each year, \"to exercise restraint, to respect the right of peaceful protest.\"