By Edmund Blair and Marwa Awad
CAIRO (Reuters) - Opponents of Egypt's President Mohamed Mursi scuffled with his supporters on Friday during a demonstration that posed the first test of the Islamist leader's popularity on the street.
Egyptians had been nervous that an anti-Mursi protest, flagged for several weeks, could turn violent and in Cairo's Tahrir Square rival groups hurled stones at each other. Some wielded sticks and charged their opponents.
Scenes were calmer in other areas of the city where Mursi's opponents also gathered. But total numbers across the city were still relatively small by early afternoon, numbering in the hundreds. Protests tend to build later in the day in summer.
Activists behind the protest accuse Mursi of seeking to monopolize power after he wrested back powers in August that the military council, which had ruled Egypt for a year and a half, had sought to retain for itself.
But several liberal groups usually critical of the Muslim Brotherhood stayed away from the protest, including the April 6 youth movement that helped galvanize support to oust President Hosni Mubarak in 2011.
Those declining to demonstrate did so either because they felt it was too early to judge Mursi, two months into his presidency, or that any challenge should be by ballot box and not on the street.
"Wake up Egyptian people. Don't fall for the Brotherhood," said Mahmoud, in his 50s, addressing about 200 people in Tahrir Square. "Egypt is for all Egyptians, not only one group."
The violence flared when bangs went off nearby, but it was not clear if they was caused by a weapon, fireworks or something else, a Reuters witness said.
Some Tahrir demonstrators chanted: "What does the (Brotherhood's) guide want? He wants everyone to kiss his feet," a reference to the spiritual leader of the Islamist group.
The organizers, among them opposition politician Mohamed Abou Hamed, also want a probe into the funding of the Brotherhood, repressed by Mubarak during his 30-year rule but which has dominated the political scene since he was toppled.
In a headline before the protests, the daily Al Masry Al Youm called the demonstration "the first test for Mursi."
Protest organizers said they would march towards the presidential palace to protest against Mursi, sworn in on June 30 as Egypt's first president not drawn from military ranks.
"Both Tantawi and the Brotherhood stole the revolution and destroyed Egypt," said Mohsen Abed Rabuh, a government worker, referring to Field Marshal Hussein Tantawi, Egypt's interim ruler, who was dismissed by Mursi this month.
He was speaking in Cairo's Abbasiya area, near the Defence Ministry, where dozens of protesters had gathered and more were congregating. It was the site of clashes between protesters and soldiers earlier this year when the army was still in charge.
The road leading to the ministry was cordoned off.
Security officials said they would protect peaceful protests but would act firmly against any lawbreakers after speculation in the press and social media that protesters could target Brotherhood premises.
The protest's Facebook page said it would be peaceful.
April 6 said in a statement before the protest that it disagreed with the Brotherhood on many issues but added: "Does all that and more push us to issue a judgment now to burn the group's members or premises and exile them from the country?"
Ahmed Said, head of the Free Egyptians, another liberal group staying away, wrote on Facebook: "Those who want to bring down the Brotherhood should bring them down via elections."
Mursi, propelled to the presidency by the well-organized Brotherhood, has formally resigned from the group saying he wanted to represent the whole nation in office.
Among criticisms of Mursi have been accusations that he has sought to muzzle the media. Critics point to a trial of two journalists, including the editor of the opposition newspaper Al-Dostour, for insulting the president.
Mursi went some way to deflecting criticism when he issued a law on Thursday, his first use of the legislative power that he wrested from the army, banning pre-trial detention of journalists. The Al-Dostour editor had been ordered detained just hours earlier.
Activists said more should be done.
"We welcome President Mursi's decision to ban pre-trial detention but urge thorough reform that repeals the archaic laws criminalizing the reporting of news and the expression of opinion," said Joel Simon, executive director of the Committee to Protect Journalists.
Some liberals have backed Mursi's early moves, including his August 12 decision to dismiss top generals, who were seen as obstructing civilian rule, and to cancel a decree that had given the army legislative power in the absence of the parliament.
The lower house, dominated by Mursi's Brotherhood, was dissolved by the military in June, based on a court order, shortly before the end of the presidential race.
One of the biggest tests Mursi faces is whether he can turn around the stricken economy. Anger at the gaping rich-poor divide was a major spark for the anti-Mubarak revolt.
This week, Egypt started talks for a $4.8 billion loan from the International Monetary Fund which could help rebuild confidence in a nation that was once a darling of frontier market investors.
(Additional reporting by Omar Fahmy and Ashraf Fahim; Writing by Edmund Blair; Editing by Robin Pomeroy)