Supporters of Egypt's deposed President Mohamed Morsi are continuing to stage rallies, with some clashes reported, despite a warning from the interim prime minister of an imminent crackdown on their protest camps.
Morsi supporters called for marches to begin after Friday afternoon prayers as the nation rested on the second day of the Eid al-Fitr holiday.
"The Egyptian people are continuing, and the days will only increase their determination to persist in their peaceful struggle until the country returns to the democratic path, until the coup is completely ended," the Anti-Coup Alliance said in a statement.
The pro-Morsi group called on the marchers to set off from mosques in Cairo.
Twenty-eight pro-Morsi protesters and one police officer were injured when clashes broke out between the demonstrators and police as crowds gathered outside the security directorate in Fayoum, police said.
Reuters news agency later quoted security sources saying that the clashes had taken place between several hundred supporters and opponents of Morsi.
Some of the injured suffered the effects of teargas inhalation, while birdshot wounds were also reported by the health ministry.
In separate incidents in the Nile Delta province of Gharbiya, four people were injured in fights between pro-Morsi protesters and residents near an army base, state-run Al-Ahram newspaper said. Thirteen Morsi supporters were arrested, according to Reuters.
Al Jazeera's Rawya Rageh, reporting from Cairo, said that UN Secretary-General Ban Ki-Moon on Saturday urged both sides of the divide in Egypt to show restraint and to favour dialogue over confrontation.
"(Such statements) keep up the international pressure on both sides (and) urge them to come to the negotiating table because, of course, the alternative could be a potentially ugly confrontation, something that no-one wants to see," our correspondent said.
Al Jazeera's Rory Challands, reporting from Cairo, said that demonstations at the 28 marches called by the Anti-Coup Alliance had been largely incident-free and demonstrators were largely in a celebratory mood.
The government has said it held off from breaking up the protest camps in Cairo out of respect for the holy month of Ramadan, which ended on Wednesday night, and to give foreign mediators to find a peaceful solution.
But the interim prime minister, Hazem al-Beblawi, warned late on Thursday "that the situation is approaching the moment we would rather avoid".
"The government wants to give the protesters, especially the reasonable ones among them, a chance to reconcile and heed the voice of reason," he said.
Pro-Morsi protesters had set up two protest camps in Cairo days before his overthrow on July 3 in a popularly backed military coup. They insist that they will disperse only when Morsi is reinstated.
More than 100 people, mostly Morsi loyalists, were killed in previous confrontations with police and soldiers.