Islamist backers of Egypt's deposed president Mohamed Morsi staged defiant rallies Friday, with police firing tear gas at demonstrators, after the government ordered their protest camps to be broken up.
The new marches came after US secretary of state John Kerry angered Morsi loyalists by saying said Egypt's military had been "restoring democracy" when it deposed the Islamist leader.
Meanwhile, world powers pressed both sides to resolve the impasse peacefully, with US Under Secretary of State William Burns expected in Cairo on Friday night for more talks.
Morsi supporters began to march after Friday prayers, pouring out of several Cairo mosques.
The afternoon rallies passed off peacefully, with demonstrators marching along main thoroughfares in the capital.
Early evening, they held several smaller demonstrations, including by Cairo's Media Production City in the city's outskirts, where security forces fired tear gas after protesters "tried to storm" the building, a security source told AFP.
Protesters tore up the pavement to make barriers as police in armoured vehicles fired barrages of tear gas, an AFP correspondent said.
"I am a Muslim, not a terrorist," demonstrators chanted.
Eyewitnesses also reported clashes between residents in the Alf Maskan area and Morsi loyalists after they tried to set up a protest site.
The Anti-Coup Alliance of groups calling for Morsi's reinstatement said it planned to make Alf Maskan a new sit-in site.
It also announced Friday evening marches to four security buildings in Cairo, including two army headquarters.
The marches came a day after Kerry in an interview with Pakistan's Geo television appeared to defend Morsi's ouster.
"The military was asked to intervene by millions and millions of people, all of whom were afraid of a descendance into chaos, into violence," he said.
"And the military did not take over, to the best of our judgement -- so far. To run the country, there's a civilian government. In effect, they were restoring democracy," he added.
A spokesman for Morsi's Muslim Brotherhood denounced Kerry's comments, accusing Washington of being "complicit" in the coup.
"Is it the job of the army to restore democracy?" asked Gehad al-Haddad in a statement.
Morsi's supporters have remained defiant in the face of mounting threats from the army-installed interim government.
On Thursday, the interior ministry urged those at protest sites in Rabaa al-Adawiya and Nahda squares "to let reason and the national interest prevail, and to quickly leave".
The ministry pledged "a safe exit and full protection to whomever responds to this appeal".
The state-owned Al-Ahram newspaper, quoting police sources, reported that police had prepared a plan to end the sit-ins, but had not decided when to implement it, with the cabinet still hoping for a peaceful resolution.
The stand-off has raised fears of new violence. More than 250 people have been killed since Morsi's ouster.
Diplomatic efforts to avoid further bloodshed have gathered pace.
Kerry said Friday that Egypt should "get back to a new normal" and a senior Egyptian official said US envoy Burns would arrive in Cairo for talks.
The visit comes on the heels of trips by the European Union's Middle East envoy Bernardino Leon and German Foreign Minister Guido Westerwelle.
A senior member of the Freedom and Justice Party, the political arm of Morsi's Muslim Brotherhood, said the European envoys had asked them to end their sit-ins.
Speaking after meeting Brotherhood representatives, Westerwelle warned that the situation was "very explosive" and reiterated a call for a "peaceful solution."
Morsi has been formally remanded in custody on suspicion of offences when he broke out of prison during the 2011 revolt that toppled former president Hosni Mubarak.
Prosecutors have also referred three top Muslim Brotherhood leaders, including supreme guide Mohamed Badie, for prosecution of allegations of inciting the deaths of demonstrators.
Morsi was detained hours after the coup and is being held at an undisclosed location, where his family has been unable to see him.
EU foreign policy chief Catherine Ashton met Morsi on Tuesday, later telling reporters he was "well".
Qatar, a staunch backer of Morsi's presidency, announced meanwhile that it had shipped a consignment of liquified natural gas to Egypt, in the first gesture of its kind since Morsi was deposed.