Clashes between rival demonstrators erupted on Friday in Egypt's second city Alexandria, on the eve of the final round of a referendum on a divisive new constitution pushed by Islamists.

Riot police, with orders to act "decisively," formed a barrier between several thousand Islamists and hundreds more opposition protesters and used tear gas to quell the street battles.

An eleven-storey building collapsed in the Egyptian coastal city of Alexandria on Saturday, destroying three neighboring homes and injuring at least 16 people, police said.

Witnesses said the building housed four families and a bakery, but could not give an overall number of tenants.

Saudi Arabia has assured a high ranking Egyptian delegation visiting the kingdom following Riyadh's closure of its Cairo embassy over protests that relations remain "solid", the SPA state news agency said.

Saudi Foreign Minister Prince Saud al-Faisal also told the delegation that Riyadh does not rule out that "foreign elements" could have plotted to cause the tension between the two Arab heavyweights, SPA reported late on Thursday.

Egyptian activists have called for anti-military demonstrations across the country on Friday, days after bloody clashes near the defense ministry left at least nine people dead.

Several pro-democracy movements, including April 6, as well as the powerful Muslim Brotherhood said they would be joining the protests in Cairo and the Mediterranean city of Alexandria, amid a tense political run-up to the country's first post-uprising presidential election.

President Michel Suleiman hailed on Saturday the interception of a ship suspected of delivering weapons to Syria as the Lebanese army issued a statement confirming the incident.

“The army intercepted on Friday Sierra Leone-flagged Lutfallah II ship suspected of carrying weapons and ammunition to Syria,” the statement said.

Pope Shenuda III, who died on Saturday aged 88, was a fearless champion of Egypt's Coptic Christians ready to defy the country's Muslim government, but he also took a more conciliatory tone in his final years.

An increasingly frail Shenuda, who rarely appeared in public, was faced in recent years with a spike in attacks against the Coptic community which he led for more than four decades.

The grand imam of Al-Azhar, Sunni Islam's highest seat of learning, called on Egyptian police on Wednesday not to shoot at protesters demanding democratic change as four more people died in clashes.

As thousands rallied for a fifth straight day in Cairo's iconic Tahrir Square, epicenter of the Arab Spring uprising which overthrew veteran president Hosni Mubarak in February, an opinion poll found that 43 percent of Egyptians thought the ruling military was trying to slow down or reverse its gains.

Thousands of protesters swarmed Cairo's Tahrir Square on Tuesday to demand an end to military rule, heightening tension after days of deadly clashes that threaten to derail next week's legislative polls.

The ruling Supreme Council of the Armed Forces (SCAF) began crisis talks with a number of political forces in a bid to defuse the crisis, state media reported.

Two people were killed and hundreds injured in Egypt this weekend as police fired rubber bullets and tear gas at protesters in a violent countdown to the first elections since the ouster of Hosni Mubarak.

"Down with Tantawi," hundreds of demonstrators cried in Cairo's iconic Tahrir Square, referring to the post-Mubarak military ruler Field Marshal Hussein Tantawi, as they lobbed rocks and other objects towards armed police.

Tucked away in a small warehouse on a dead-end street, an Internet pioneer is building a bunker to protect an endangered species: the printed word.

Brewster Kahle, 50, founded the nonprofit Internet Archive in 1996 to save a copy of every Web page ever posted. Now the MIT-trained computer scientist and entrepreneur is expanding his effort to safeguard and share knowledge by trying to preserve a physical copy of every book ever published.