Egyptian security forces firing tear gas clashed with more than 5,000 rock-throwing protesters in central Cairo late Tuesday, leaving dozens injured in the latest unrest to rattle the country, witnesses and medical officials said.   

Clouds of tear gas and the wail of police sirens engulfed Tahrir Square as lines of security forces in riot gear battled to regain control of the central plaza from the demonstrators, many of them family members of the more than 850 people killed during the revolution that toppled Egypt's longtime ruler, Hosni Mubarak.   

The families are frustrated with what they perceive as the slow prosecution of security officers believed to be responsible for the deaths of some 850 protesters during the 18-day uprising.   

Rocks and shattered glass littered the streets around Tahrir, as protesters chanted: "Down with the military junta." Injured demonstrators lay on the ground, some bloodied and dazed, before the clashes ended after Interior Minister Mansour el-Essawy issued an order before dawn Wednesday for the security services to stand down.   

The confrontation began Tuesday, when security forces cleared a sit-in outside the state TV building by the families of the slain protesters, said Nourredine, an engineer who gave only his first name.   

"I was in front of the state TV building this morning when the security forces attacked," he said. "Since then, things have been escalating."   

The protesters regrouped Tuesday evening outside the Interior Ministry, where rumor had it that two demonstrators wounded earlier in the day had been taken. It was not immediately clear what sparked the violence outside the ministry, but eventually protesters were hurling stones and security forces firing volleys of tear gas and blocking off streets around the building.   

The clashes then shifted to nearby Tahrir Square — the epicentre of Egypt's revolution. In a sight unseen since the early days of the uprising, lines of central security troops in riot gear sealed off the main streets leading into the square, while dozens of security vehicles were parked in side streets.   

The government response shocked many of the protesters, who compared it to the heavy-handed tactics used by the security forces before Mubarak's fall.   

"The security forces' violence is the same," said Al Maataz Hassan, an engineer. "They accuse the people of being thugs, then crack down. It's the same mentality as before the revolution."

Rocky road to change

Tuesday's clashes, the most serious between security forces and protesters since Mubarak's ouster on Feb. 11, are a symptom of the tumultuous transitional period the country is going through as it attempts to shift from an authoritarian to democratic system.

That transition took a step forward early Tuesday with an Egyptian court's ordering the dissolution of more than 1,750 municipal councils, seen as one of the last vestiges of Mubarak's rule.

The administrative court decision, announced by presiding judge Kamal el-Lamei, meets a major demand of the protest movement that drove Mubarak from the presidency in an 18-day uprising early this year.

The local councils, with more than 50,000 seats filled by elections widely viewed as rigged, were a backbone of support for Mubarak's ruling party. They became particularly important after 2005 constitutional amendments required presidential candidates to obtain support from a quota of local council officials, as well as from national parliament members. Critics saw this as a stepping stone for Mubarak's son, Gamal, to succeed his father in office.

The court decision can still be appealed, but popular opposition may make it difficult for Egypt's current military rulers to challenge it.

Hamdi el-Fakharani, an engineer who filed the court case against the councils, said 97 per cent of council members belonged to Mubarak's now-dissolved National Democratic Party.

"They had already begun campaigning, using municipal services to influence people in favour of the party's comeback and saying the revolution has negatively impacted the economy," he said.