Islamist supporters of Egypt's ousted president, Mohamed Morsi, protested in Cairo on Friday after a week of violence in which more than 90 people were killed in a bitterly divided nation.
More than a week after the army toppled Egypt's first elected leader after a wave of demonstrations against him, Morsi's Muslim Brotherhood is trying to mobilize popular support for his reinstatement, which for now looks like a lost cause.
At a Cairo mosque where Morsi supporters have held vigil for more than two weeks, crowds swelled as people were bused in from the provinces, where the Brotherhood has strongholds.
The streets of Cairo were otherwise quiet on Friday, the weekly Muslim day of prayer, in the holy month of Ramadan.
The youth-led Tamarud group, which brought millions of people to the streets to demand Morsi resign, has called for a Ramadan celebration in Tahrir Square, the cradle of the uprising that overthrew President Hosni Mubarak in 2011.
Officials say Morsi is still being held at the Republican Guard compound in Cairo, where troops killed 53 Islamist protesters on Monday in violence that intensified anger his allies already felt at the military's decision to oust him.
Four members of the security forces were also killed in that confrontation, which the military blames on "terrorists". Morsi's supporters call it a massacre and say those who died were praying peacefully when troops opened fire.
Many of Egypt's 84 million people have been shocked by the shootings, graphic images of which have appeared on state and private news channels and social media. The incident occurred just three days after 35 people were killed in clashes between pro- and anti-Morsi demonstrators across the country.
"It's a very hard time for Egyptians, to see footage of blood and violence during the holy month of Ramadan, and everyone I speak to says the same thing," said Fateh Ali, a 54-year-old civil servant in Cairo.
The Brotherhood contends it is the victim of a military crackdown, evoking memories of its suppression under Mubarak.
But many of its opponents blame Islamists for the violence, and some have little sympathy for the demonstrators who died, underlining how deep the fissures in Egyptian society are.
The unrest has also raised fear over security in the lawless Sinai peninsula bordering Israel and the Palestinian Gaza Strip.
Militant groups in North Sinai have promised more attacks and urged Islamists to take up arms, while the army has vowed to step up operations in the region, which is near the Suez Canal, the busy waterway linking Asia and Europe.
One Egyptian policeman was killed and another wounded early on Friday when militants fired rocket-propelled grenades at checkpoints in the Sinai town of El Arish.
Egyptian state media said police arrested three Palestinian militants for attempted attacks in Sinai.
VIGIL, SONGS FOR THE DEAD
Outside the Rabaa Adawiya mosque in northeastern Cairo, thousands of Brotherhood supporters gathered late on Thursday to mourn the dead in Monday's violence, the deadliest since Mubarak was toppled, apart from a 2012 soccer stadium riot.
Women wailed and men cried as they watched a large screen showing grim footage of hospital scenes immediately after the shooting, with corpses on the floor and medics struggling to cope with the number of bloodied casualties being carried in.
Hundreds of Egyptian flags fluttered. Songs of defiance were sung. Thousands of Islamists have camped out in searing heat, fasting in the daytime since Ramadan began on Wednesday.
"This is a bloody military coup," said Saad Al-Husseini at the vigil. "This is the biggest crime I have witnessed in my country's recent history. Never before has blood been so cheap."
The camp has become the de facto base of the Brotherhood, whose leaders live under the threat of detention after the public prosecutor ordered their arrests earlier in the week.
Judicial sources say Morsi is likely to be charged, possibly for corruption or links to violence. Prosecutors are also looking again at an old case from 2011 when Morsi and other Brotherhood leaders escaped from prison after being detained during anti-Mubarak protests.
The detentions and threats of arrest have drawn concern from the United States, which has walked a semantic tightrope to avoid calling Morsi's ouster a military coup.
U.S. law bars aid to countries where a democratic government is removed in a coup. Washington, which gives Egypt's military $1.3 billion in aid each year, has said it is too early to say whether Morsi's removal by the army meets that description.
The army has said it was enforcing the nation's will - meaning the huge crowds of people fed up with economic stagnation and suspicious of a Brotherhood power grab who took to the streets in late June to demand Morsi's departure.
State Department spokeswoman Jen Psaki said on Wednesday Morsi's government "wasn't a democratic rule".
Her words were warmly received by the interim government and swiftly denounced by the Brotherhood. On Thursday, Psaki expressed concern over the crackdown on Brotherhood leaders.
"If politicized arrests and detentions continue, it is hard to see how Egypt will move beyond this crisis," she said.
German's foreign ministry demanded that Morsi be freed.
Crucial to longer-term stability will be holding parliamentary and presidential elections, which the transitional authorities are hoping to achieve in a matter of months.
Adli Mansour, the interim president named by the general who removed Morsi, has announced a temporary constitution, plans to amend it to satisfy parties' demands and a faster-than-expected schedule for parliamentary elections in about six months.
He has named liberal economist Hazem el-Beblawi as interim prime minister, and Beblawi said he had named leftist lawyer Ziad Bahaa el-Din as his deputy. Beblawi also said he would contact candidates for ministerial posts on Sunday and Monday, with a view to swearing in a cabinet next week.
Negotiations are difficult, with the authorities trying to attract support from groups that range from secularists to ultra-orthodox Muslims, nearly all of whom expressed deep dissatisfaction with elements of the interim constitution.
Underlining the level of concern overseas at Egypt's crisis, two U.S. Navy ships patrolling in the Middle East moved closer to Egypt's Red Sea coast in recent days, in what appeared to be a precautionary move following Morsi's ouster on July 3.
The United States often sends Navy vessels close to countries in turmoil in case it needs to protect or evacuate U.S. citizens or give humanitarian assistance.
Rich Gulf states have thrown Egypt a $12 billion lifeline in financial aid, which should help it stave off economic collapse.
More than two years of turmoil have scared away tourists and investors, shriveled hard currency reserves and threatened Cairo's ability to import food and fuel.
Additional reporting by Alexander Dziadosz, Sarah McFarlane, Mike Collett-White, Tom Finn, Peter Graff, Ali Saed, Seham el-Oraby and Shadia Nasralla in Cairo and Andrea Shalal-Esa and Lesley Wroughton in Washington; Writing by Mike Collett-White and Peter Graff; Editing by Alistair Lyon