Around 100 protesters calling for an end to military rule in Egypt clashed with soldiers near the US embassy in Cairo, an AFP correspondent reported.
Shouting "Down with military power!" the protesters lobbed stones at the soldiers, who responded by throwing them back and trying to disperse the crowd.
The soldiers then returned to their position, where they were joined by a group of civilians, who also threw stones at the protesters.
Earlier, two civilian groups, one of them demanding the expulsion of the US ambassador, had clashed in front of the embassy, hurling stones at each other.
After months of pressure from Washington, 13 foreign defendants accused of receiving illicit foreign funds to operate unlicensed NGOs, including six Americans, were allowed to leave the country after posting bail last week, sparking outrage in Egypt.
A travel ban was lifted after the trial judges recused themselves in the face of what they said was intervention by the authorities.
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During the day, around 200 people marched in nearby Tahrir Square, the epicentre of last year's uprising that toppled president Hosni Mubarak and saw the Supreme Council of the Armed Forces take power.
The protesters there marked the day, one year ago, when the army dispersed a crowd in Tahrir Square by force and arrested a group of women protesters.
After being beaten, the detained activists were forced to undergo "virginity tests," a practice classified as torture and sexual violence by Egyptian and international rights groups, including Amnesty International and Human Rights Watch.
Amnesty said the verdict, due on Sunday, in the trial of a military doctor accused of carrying out the tests, "will show if Egypt's military courts are prepared to offer any redress for female victims of violence by the army."
Egypt's judiciary last year ordered the army to halt the practice.
The London-based rights group also called on Friday for "thorough, impartial and independent investigations" to be carried out into all complaints by women who were subjected to violence by Egypt's army and security forces over the past year.