CAIRO – Stone-throwing clashes broke out Friday in the Egyptian city of Alexandria between Islamists and opposition protesters, on the eve of a highly charged referendum on a new constitution, witnesses and state media said. Muslim clerics urged worshippers to vote “yes,” while thousands of supporters and opponents of a controversial draft constitution filled the streets of Cairo Friday in dueling protests. Religious authorities had issued orders that mosques should not be used to manipulate the vote, but several clerics, especially in conservative southern areas, took to the pulpit to tell their congregations that voting in favor of the constitution is seeking victory for Islam. “Voting yes is like jihad,” Sheik Abdel-Akher Hamad told worshippers in the southern city of Assuit. “It preserves Egypt from evils and from those who want to sabotage Islam and Muslims.” Police in riot gear moved to restore order in Alexandria, Egypt's second-biggest city. Tensions are high over the staggered referendum, which is being held on this and the following Saturday, after weeks of protests and violence between rival camps in Cairo last week that killed eight people and injured hundreds. Further mass rallies were taking place in Cairo by both sides. A pro-constitution rally by the Muslim Brotherhood backing Morsi gathered more than 2,000 people. Egypt's mainly secular opposition has slammed the draft charter as divisive and a possible attempt by Islamists to introduce Shariah law. Mohamed ElBaradei, a former UN nuclear energy agency chief who heads the opposition National Salvation Front, said on his Twitter feed: “Insistence on referendum in an explosive, polarized, chaotic and lawless environment is leading country to the brink.” The Front Friday was holding last-ditch rallies against the new constitution. It has said it could yet call a boycott if its “deep concern” over the referendum's fairness turns out to be founded. Morsi has ordered Egypt's military to help police maintain security until the results of the referendum are known. A total of 130,000 police and 120,000 soldiers will be deployed, interior ministry and military officials said. – Agencies