Egyptian Islamists have called new demonstrations in a test of strength against the army.
Islamist supporters of ousted Egyptian president Mohamed Morsi have called new protests against the army in a test of their ability to mobilise support seven weeks after his overthrow.
In recent days, dozens of senior and mid-level members of Morsi's Muslim Brotherhood have been arrested, disrupting the organisation's structure, and raising questions about its remaining strength.
The call for demonstrations by loyalists of Morsi, who remains in custody at a secret location, came a day after his predecessor Hosni Mubarak was released from jail to house arrest at a military hospital.
The release stirred little interest in Egypt, which has been rocked by political unrest since Morsi's July 3 ouster by the military after massive protests against him.
Nearly 1000 people were killed in a week of violence between Morsi loyalists and security forces, sparking international concern and condemnation.
Friday was set to be a test of the remaining strength and commitment of the Islamists, who called for "Friday of martyrs" protests after the main weekly Muslim prayers.
In recent days, dwindling numbers of demonstrators have showed up to rallies, their ranks thinned by a fierce crackdown.
Communication by telephone has stopped altogether, and many Brotherhood members are in hiding, avoiding their homes, a mid-level member of the group told AFP on condition of anonymity.
"We no longer receive directives and we don't really know what we should do anymore. Most of our direct leaders are detained," the member from the Nile Delta said.
Among those detained is the group's supreme guide Mohamed Badie - the first time a Brotherhood chief has been arrested since 1981.
Morsi himself is being held at a secret location and faces charges related to his 2011 escape from prison and of inciting the death and torture of protesters.
His continued detention even as Mubarak is released to house arrest has stirred comment, particularly as Mubarak also faces charges of complicity in the deaths of protesters.
But in the face of the deadly unrest that has rocked Egypt in recent days, there was no indication that activists would take to the streets, as they have done before, to protest Mubarak's transfer.
"A year ago, it would have been difficult to imagine his release without popular protests against it," said Barah Mikail, a Middle East specialist at the FRIDE think-tank.
"Today, everything else that is happening has moderated the effect".
Mubarak is still on trial and faces his next court session on Sunday, when Badie and several other Brotherhood leaders will also appear before a court.
Washington on Thursday sidestepped questions about Mubarak's release from jail, but called for Morsi to be freed.
"With respect to the Mubarak trial and decisions made, this is an internal Egyptian legal matter," said State Department spokeswoman Jen Psaki.
"Our position on Mr Morsi remains the same. We believe there should be a process for his release," Psaki said
But there has been no sign that a crackdown against the Brotherhood will slow.
The latest arrest was that of Ahmed Aref, one of the few remaining spokesmen for the group who had not been detained.
At the same time, attacks against Christian institutions, which have been blamed on Islamists, have continued.
Dozens of Christian churches, schools, businesses and homes - mostly in the rural south - have been attacked, allegedly by Islamists angry at the Coptic Church leadership's endorsement of Morsi's ouster.
On Thursday, Human Rights Watch condemned the government for failing to protect churches, and the Brotherhood for failing to halt incitement against Christians.
Violence has also continued to target police and soldiers, including three who were killed in a drive-by shooting near the Suez Canal town of Ismailia on Thursday.
The unrest has prompted international criticism of the authorities, but the United States has stopped short of halting its $US1.3 billion ($A1.45 billion) a year in mainly military aid.