The United States joined Germany's call on Friday for deposed Egyptian President Mohamed Morsi to be released.
Asked if the United States agreed with the German Foreign Ministry's call for Morsi to be released, State Department spokeswoman Jen Psaki told reporters "We do agree."
Morsi has been detained at an undisclosed location since he was toppled.
Speaking at her daily briefing, Psaki also said she could confirm that US Ambassador to Egypt Anne Patterson has met Egypt's interim president, who was appointed by the military.
Meanwhile, Islamist Morsi supporters protested in Cairo on Friday after a week of violence in which more than 90 people were killed in a bitterly divided nation.
Nine days after the army toppled Egypt's first elected leader following 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 bussed in from the provinces, where the Brotherhood has strongholds.
"We're here and we're not leaving," said Amer Ali, who drove the five-hour journey from the Nile city of Assiut with his wife and two young children to join tens of thousands of protesters.
"We came with our kids to support legitimacy, democracy, and our civilian president, the first freely elected president in the Arab world."
Some 2,000 people had gathered close to Cairo University on 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.
Shock and anger
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.
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.
An Egyptian military helicopter briefly crossed into Israeli-controlled airspace over the Gaza Strip, in a possible sign of increased security jitters.
Security sources in Egypt and Israel both described the flyover as a navigational error, but it came shortly after militants killed an Egyptian policeman and wounded a second in an attack on a checkpoint in Sinai across the border from Gaza.
Vigil enters third week
Outside the Rabaa Adawiya mosque in northeastern Cairo, tens of thousands of Brotherhood supporters prayed and listened to speeches. Some of them have camped out in searing heat, fasting in the daytime since Ramadan began on Wednesday.
In a wooden shack erected on a side street and emblazoned with portraits of Morsi, men prepared vats of rice and lamb. Others put the food in plastic bags to distribute after sundown, when Muslims break their fast.
People squirted water from bottles to cool each other down. Others rested in the shade, dozing or reading the Koran.
The night before, they had mourned Monday's dead, killed in the worst violence since Mubarak was toppled, apart from a 2012 soccer stadium riot. "Never before has blood been so cheap," said Saad Al-Husseini.
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.
His son Osama told CNN that he was proud of Morsi. "We back any decision you take. Even if you decided to leave the office. Your family, we are all proud of you, God bless you," he said in English.
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.
US 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".
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 centre-left lawyer Ziad Bahaa el-Din as his deputy. Beblawi also said he expected to swear 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 US 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 US 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.