Egypt's political crisis deepened on Sunday, with supporters of the ousted president defiant as the National Defence Council warned it would take "decisive and firm" action if protesters overstepped.
EU foreign policy chief Catherine Ashton arrived in Cairo on Sunday evening for talks with a range of political figures, including Vice President Mohamed ElBaradei, who said in a statement that the country wanted "to achieve a peaceful solution to the current crisis."
But tensions remained high after the deaths of 72 people at a demonstration in support of deposed president Mohamed Morsi in Cairo on Saturday morning, the bloodiest incident since his ouster.
In its first comments on the incident, Egypt's presidency said it was "saddened" by the bloodshed, but added that it came in a "context of terrorism."
Sporadic violence continued throughout the country, with at least three people reported dead in separate clashes.
Egypt's vice presidency said Ashton would meet with interim president Adly Mansour and ElBaradei, who is vice president for international affairs.
State news agency MENA said she would also hold talks with members of Morsi's Muslim Brotherhood and the Tamarod group that organised the protests that preceded his ouster.
Earlier, Egypt's presidency addressed the 72 deaths for the first time.
"We are saddened by the spilling of blood on the 27th," Mansour adviser Moustafa Hegazy told reporters.
But he dubbed the protest area where the deaths occurred a "terror-originating spot" and said "we cannot decouple this from context of terrorism."
Interior minister Mohamed Ibrahim also warned his forces would "not allow any mercenary or person bearing a grudge to try to disrupt the atmosphere of unity."
"We will confront them with the greatest of force and firmness," he said.
Morsi loyalists, still camped out at the scene of Saturday's violence, were defiant.
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"There are feelings of agony and anger, but also a very strong feeling of determination," Brotherhood spokesman Gehad el-Haddad told AFP.
"For us, if we die, we meet our creator and we did so for a just cause... Either we die or we succeed."
Saturday's violence, which came after a night of rival protests for and against Morsi, was the bloodiest incident since Morsi's July 3 ouster following huge demonstrations against his rule.
Sporadic violence continued on Sunday, with a security source reporting three people killed in clashes between Morsi supporters and opponents in Port Said and northern Kafr El-Zayat.
The country's divisions were evident in the divergent narratives of Saturday's events, with Morsi's supporters saying they were targeted with live fire and the interior ministry insisting only tear gas was used.
The National Defence Council meanwhile warned protesters on Sunday night "not to exceed their rights to peaceful, responsible expression of their opinions," saying they would face "decisive and firm decisions and actions in response to any violations."
The council is presided over by Mansur, and includes the army chief as well as the prime minister and interior minister.
It also called on Morsi loyalists to "immediately announce their clear and categorical rejection of violence in all forms, and the immediate cessation of violence, terrorism and the verbal and physical abuse of citizens."
Saturday's violence prompted international concern, including from US Secretary of State John Kerry, who called on authorities to "respect the right of peaceful assembly and freedom of expression."
US Democratic Senator Dianne Feinstein said her government should "relook at granting aid" to Egypt.
ElBaradei on Saturday night also denounced the "excessive use of force" against protesters, but the National Salvation Front -- a liberal and leftist grouping -- said Morsi's supporters bore some blame for their "provocative approach."
The violence came after army chief General Abdel Fattah al-Sisi, who led the coup that ousted Morsi, called for demonstrations to support a crackdown on "terrorism."
Morsi, who was elected after a 2011 uprising, has not been seen since his July 3 ouster and is being held on accusations related to his escape from prison during the protests that overthrew former president Hosni Mubarak.