Protests turn violent in Egypt ahead of vote on constitution

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(CNN) -- Riot police fired tear gas at protesters in the Egyptian city of Alexandria on Friday, according to state-run Nile TV. Shortly after morning prayers, clashes broke out between supporters and opponents of President Mohamed Morsy.

Read more: Morsy backers accused of beatings, detentions

There were at least 1,000 people in the crowd, and about 300 of them threw rocks at police, a witness said.

The fighting broke out new the Al-Qaed Ibrahim Mosque, the site of similar fighting last Friday. The clashes were apparently inspired by the mosque's imam, Sheikh Ahmed El-Mahlawy, according to journalist Abdelrahman Youssef, who was at the site of the protest.

Read more: Egypt's prosecutor general quits amid protest

The imam encouraged people to demonstrate about a dispute among Egyptians and their government over whether the country's new constitution is legitimate, he said.

Last month, the constitution was drafted by an Islamist-dominated assembly that included people from all walks of life, including judges and religious leaders. Egyptian citizens are going to the polls to give it final approval.

Read more: Islamists claim victory in first round of referendum

Many in Egypt felt the draft constitution was passed too quickly. They are suspicious that it uses vague language and will not guarantee the rights of the people that Egyptians fought for during a revolution that unseated President Hosni Mubarak in 2011.

The draft constitution, some said, was a way for Morsy to give himself unchecked power.

Read more: News agency say Mubarak hurt in prison bath fall

The first round of voting on the constitution happened last weekend. Then, Egypt's ruling Freedom and Justice Party declared that the people had approved it.

But a coalition of 123 local rights groups that monitored last Saturday's referendum alleged widespread abuses. Egypt's electoral commission acknowledged that it received complaints of voter intimidation, bribery and other violations.

The commission said it would not announce official results until after the second phase of voting this Saturday.

CNN's Reza Sayah, Saad Abedine and Mitra Mobasherat contributed to this report.