CAIRO: Rival factions Thursday condemned violence which has killed dozens of people in a week of unrest in Egypt, and pledged support for a national dialogue, as the opposition called fresh rallies set for Friday.

Top Islamic scholar Grand Imam Ahmed al-Tayyeb chaired talks between liberal opposition heads, Islamists, youth groups, independents and church members at the headquarters of Al-Azhar, Sunni Islam's highest seat of learning.

They signed an Al-Azhar document vowing to support "a serious dialogue" and "condemn all forms of violence and incitement to violence," and stressing "the responsibility of the state and its security apparatus to protect citizens."

But the opposition at the same time urged mass protests on Friday against President Mohamed Morsi, who is accused of betraying the revolution that brought him to the presidency and of consolidating power in the hands of the Muslim Brotherhood.

In a statement, the National Salvation Front (NSF) said Egyptians should demonstrate nationwide against "a regime that seeks to impose its will on the people and is managing the country in the interest of the Brotherhood."

In Cairo, marches will head to Tahrir Square and the presidential palace.

The interior ministry said it respected "the right to peaceful protest," but urged all political forces to ensure "a peaceful and civilised" day, a spokesman said.

Egypt has been gripped by unrest since rallies last week marking the second anniversary of the uprising that toppled president Hosni Mubarak.

The protests turned violent on Saturday after a Cairo court sentenced 21 residents of the canal city of Port Said to death for their involvement in football-related violence last year.

Friday's protest will mark one year since the Port Said clashes that left 74 people dead.

In the capital, the health ministry said two more people had died from their injuries following the clashes, bringing to 56 the number of deaths nationwide in a week of violence.

It remained to be seen whether the Al-Azhar document would carry weight on the street.

Opposition and NSF leader Mohamed ElBaradei, a former UN nuclear watchdog chief, praised the Al-Azhar talks.

"We come out of these talks with some sort of optimism" despite "the difficult challenges ahead," he told reporters.

"We will do whatever we can with goodwill to build the trust of the Egyptian people."

Saad al-Katatni, head of the Freedom and Justice Party of the Muslim Brotherhood, stressed the need for compromise.

"There is no solution to the problems in our path to democracy without dialogue... Dialogue must have guarantees but no preconditions," he said.

"All topics are up for discussion and all participants said they were ready for compromises," Katatni told reporters.

Even with few concrete points agreed, Thursday's talks marked a blow for Egypt's Islamist president whose calls for dialogue were snubbed by the opposition only last week.

In a statement, the presidency welcomed the document as "an important step on the road to re-establishing stability."

At the opening remarks of the Al-Azhar talks, Tayyeb said a "national dialogue including all segments of society is the only way to resolve all the differences."

Such a dialogue would constitute a "guarantee against the monopolisation of power which leads to tyranny," he said.

The meeting was the latest attempt to strike up a dialogue between political factions in a country deeply split between Morsi's Islamist allies and an opposition of leftists, liberals, Christians as well as religious Muslims.