Egyptian Vice President Mahmoud Mekki announced his resignation on Saturday, the day of a referendum on a new constitution that leaves unclear whether his position would be maintained.

In a statement obtained by AFP, Mekki said he was stepping down because "political work does not suit my professional character as a judge."

Egyptians voted on Saturday in the final round of a referendum on a new constitution championed by President Mohamed Morsi and his Islamist allies, but with little prospect of the result quelling fierce protests.

On the eve of polling, clashes in Egypt's second city Alexandria injured 62 people as stone-throwing mobs torched vehicles, underlining the turmoil gripping the Arab world's most populous nation.

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.

Jordan said on Thursday Egypt has resumed full gas supply of 250 million cubic meters (8.8 billion cubic feet) a day to the energy-poor kingdom, after the flow was disrupted by repeated pipeline attacks.

"In the past few days, we received between 190 and 210 million cubic meters of gas from Egypt. But today Egypt resumed full supplies of 250 million cubic meters," Prime Minister Abdullah Nsur told a joint news conference with his Egyptian counterpart Hisham Qandil.

Egypt's chief public prosecutor on Thursday retracted his resignation, days after offering to step down following protests by prosecutors and judges against his appointment by President Mohammed Morsi.

Talaat Ibrahim Abdallah, who offered his resignation earlier this week, asked to be allowed to remain on in his position, the official MENA news agency reported.

A court in Egypt on Thursday ordered a retrial of two policemen jailed for beating a young man to death in a shocking case that helped spark the country's revolution in early 2011.

The Court of Cassation overturned seven-year prison sentences handed to officers Mahmoud Salah Mahmoud and Awad Esmail Suleiman in October 2011 for the beating death of 28-year-old Khaled Saeed in the Mediterranean city of Alexandria in June the previous year.

Egypt's ousted president Hosni Mubarak was transferred to a Cairo military hospital on Wednesday, after slipping and injuring his head and chest in prison, a security official said.

For months, there have been conflicting reports about the health of the 84-year old Mubarak, who was sentenced in June to life in prison for failing to stop the killing of hundreds of protesters during last year's uprising. He is the first Arab president to serve a prison sentence.

International peace envoy to Syria Lakhdar Brahimi is expected to visit Lebanon during his upcoming tour of the region, al-Liwaa newspaper reported on Wednesday.

Diplomatic sources told the newspaper that Brahimi will arrive in Beirut after a short visit to Egypt and Syria after President Bashar Assad sets the date for a meeting.

Hundreds of protesters demonstrated in front of the Cairo palace of Islamist President Mohamed Morsi late on Tuesday in a last-ditch bid to scuttle a draft constitution being put to a referendum.

The rally, of up to 2,000 people according to AFP correspondents, was smaller than previous anti-Morsi protests held over the past three weeks.

Egypt's prosecutor general named by President Mohamed Morsi last month as he temporarily assumed sweeping powers handed in his resignation on Monday, a judicial source told Agence France Presse.

"The prosecutor general has submitted his resignation under pressure from protesters," said the source, referring to magistrates who have been clamoring for his immediate departure.