Egyptian opposition leaders on Wednesday sought urgent talks on the political crisis gripping the country, as fresh violence killed two more people in Cairo.
Mohamed ElBaradei, a leading figure in the National Salvation Front, called for the talks just two days after the opposition had rejected Islamist President Mohamed Morsi's appeal for dialogue.
"We want an immediate meeting between the president, the ministers of defence and interior, the ruling party, the Salafist movement and the National Salvation Front to take urgent measures to end the violence and begin a serious dialogue," ElBaradei tweeted.
Former Arab League chief Amr Mussa, another NSF leader, said "the serious current situation" required the acceptance of dialogue "in order to stop the confrontations and the violence."
It was not immediately clear whether this represented a step back by the NSF, which had been demanding a national salvation government and amendment of the Islamist-drafted constitution before agreeing to talks.
But Khaled Dawoud, spokesman for ElBaradei's Al-Dustur party, said ElBaradei's statement was a "denial of all the claims by the presidency that we reject dialogue.
"We are looking for a way out of this (crisis) because we're extremely worried."
The latest unrest began with protests marking the second anniversary of the Egyptian uprising, and took a violent turn at the weekend after 21 residents of Port Said were sentenced to death over football-related violence.
On Wednesday, Fitch ratings downgraded Egypt's long-term foreign and local currency ratings from B+ to B, with a negative outlook, citing political instability, a weaker economy and diminishing foreign reserves.
Anger on the streets has been directed primarily at Morsi, who is accused of betraying the revolution that brought him the presidency and of consolidating power in the hands of his Muslim Brotherhood.
Scrambling to contain the unrest, Morsi on Sunday slapped the three riot-hit provinces with a curfew from 9:00 pm until 6:00 am, provoking more protests.
On Wednesday, the governors of Suez and Ismailiya eased the curfew to run from 2:00 am to 5:00 am. In Port Said, scene of the deadliest unrest, curfew hours were reduced to 1:00 am to 5:00 am, state media reported.
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On Wednesday afternoon, leaders of the NSF -- which groups mainly liberal and leftist parties -- held talks with the Salafist Al-Nour party in response to an invitation from the ultra-conservative Islamist group to discuss the crisis.
They agreed to discuss the formation of a national salvation government and amendment of the constitution.
"One single faction cannot be responsible for managing the affairs of the state," said Al-Nour chief Yunes Makhyun.
"We are concerned for the public interest. Our ideologies may be different but we are all children of one country."
In Cairo, two people were killed near Tahrir Square on Wednesday. Their identities unknown, but medics said they had both been hit by buckshot.
Their deaths bring to four the number of people killed in Cairo and 54 the nationwide total since violence erupted late Thursday, prompting Defence Minister General Abdel Fattah al-Sissi, to warn the crisis could lead to "a collapse of the state."
Most of the deaths were in Port Said on Saturday after a court issued death sentences against 21 supporters of local football club Al-Masry for their role in deadly riots last year.
Also in Cairo, authorities detained four suspected Black Bloc members as they protested against an order by the public prosecutor to arrest anyone from the shadowy opposition group.
As the call for dialogue was made, Morsi was in Berlin for talks with Chancellor Angela Merkel who urged him to ensure dialogue remains an option.
"From my side I made it clear that there are different things that are very important for us," she said, adding: "One is that dialogue with all political forces in Egypt is always available."
Germany's foreign minister earlier warned financial aid to Egypt was contingent upon democratic progress.
Morsi had also been due to meet French President Francois Hollande on Friday, when the Egyptian opposition has called rallies, but the French presidency said his visit has been postponed.