Egypt protests: Death toll up in Cairo's Tahrir Square
On Sunday, police and troops made a violent attempt to evict the demonstrators, firing tear gas and beating them with truncheons.
However, the protesters returned less than an hour later, chanting slogans against Egypt's military rulers.
The European Union said it condemned the violence "in the strongest terms".
There were also clashes in other cities including Alexandria, Suez and Aswan.
A total of 11 people were reportedly killed on Sunday and two on Saturday, according to medical sources. Health officials say as many as 900 have been injured, including at least 40 security personnel.
The demonstrators, some wearing gas masks, say they fear Egypt's interim military rulers are trying to retain their grip on power.
The violence comes a week before the country's first parliamentary elections since President Hosni Mubarak was overthrown in February.
Armoured vehicles
The European Union's foreign policy chief Catherine Ashton called on the Egyptian authorities to cease violence against the protesters.
"I urge calm and restraint and condemn the use of violence in the strongest terms. There is no doubt that the transitional process is a difficult and challenging one," she said.
"I reiterate that the interim authorities and all parties concerned have the crucial task of listening to the people and protecting their democratic aspirations."
A second day of violence began on Sunday when stone-throwing protesters advanced from the square - focal point of February's uprising - towards the interior ministry; Kazinform cites BBC.
To learn more go to www.bbc.co.uk
