Violent clashes today returned to the streets of Egypt as Islamist supporters and largely secular opponents of a controversial draft constitution hurled stones at each other, a day before the final round of a referendum on the new charter.

Several thousand demonstrators backing President Muhammed Mursi gathered in northern port city of Alexandria's Qaed Ibrahim Mosque for Friday prayers to "defend (Islamic) scholars and mosques", and to call for Sharia (Islamic law).

The rally, which was initially peaceful, turned violent when clashes broke out between Islamist demonstrators and rival opposition group. Clashes seem to have been kicked off after opposition protesters picked a fight with one of the Islamist demonstrators, Egyptian media reported.

Security forces, who were heavily deployed early today near the rallying point as a pre-emptive measure against possible violence, worked to restore order and fired rounds of teargas into the crowds. According to Egyptian newspaper 'Al-Ahram', tens of fire engines and ambulances are also situated in the area.

"The people want the implementation of God's Sharia," the crowds say, "we sacrifice our soul and our blood for Islam." The protest comes after iconic Alexandria Sheikh Ahmed El-Mahalawy was held captive inside the mosque for 14 hours last Friday by worshippers angered by the overt Islamist rhetoric in his sermon.

El-Mahalawy demanded worshippers seek the implementation of Sharia (Islamic law) ahead of the referendum's first round, which was regarded as a call to vote 'Yes' for the charter.

Over 20 people were injured last Friday in the ensuing confrontations and a few vehicles were set alight. The first round of referendum last week saw almost 44 per cent of Egyptians saying 'No' to the constitution drafted by an Islamist-dominated Constituent Assembly, with a second round set for tomorrow.

Egypt's Constituent Assembly on November 30 in a marathon session approved the draft constitution imposing Islamic values, a move opposed by Liberals as an attempt to restrict freedom of speech and religion in the country. The articles passed, stipulated that Islam is the religion of the state, and the principles of Sharia, or Islamic law, are the "main source of legislation".

Meanwhile, last-minute campaigning was taking place ahead of the final round of plebiscite tomorrow. Yesterday, Egypt's top election official overseeing the referendum resigned citing health reasons, amid widespread allegations of irregularities and rigging.

A number of rights groups and opposition parties had filed complaints of violations during the first round of the vote. They complained that at several places a vote was held without a judge overseeing it and at several places judges were replaced by employees.

Egypt's Justice Ministry has ordered an investigation into the allegations. Many judges had also boycotted overseeing the referendum, in protest against President Mursi's action of "abduction" of the Supreme Constitutional Court.