CAIRO - Police in Cairo fired tear gas on Wednesday at hundreds of stone-throwing Egyptian youths after a night of clashes that injured more than 1,000 people, the worst violence in the capital in several weeks.

Nearly five months since a popular uprising toppled Hosni Mubarak, Egypt's military rulers are struggling to keep order while a restless public is still impatient for reform.

Protesters are seen in front of smoke after burning a police booth in front of the Interior Ministry in Cairo June 29, 2011. [Photo/Agencies]

The latest clashes began after families of people killed in the uprising that ousted Mubarak held an event in a Cairo suburb late on Tuesday in their honour.

Other bereaved relatives arrived to complain that names of their own dead were not mentioned at the ceremony. Fighting broke and moved towards the capital's central Tahrir Square and the Interior Ministry, according to officials.

The Health Ministry said 1,036 people were injured, among them at least 40 policemen.

The ruling military council said in a statement on its Facebook page that the latest events "had no justification other than to shake Egypt's safety and security in an organised plan that exploits the blood of the revolution's martyears and to sow division between the people and the security apparatus."

Prime Minister Essam Sharaf told state TV he was monitoring developments and awaiting a full report on the clashes.

A security source quoted by the state news agency MENA said 40 people were arrested, including one US and one British citizen, and were being questioned by military prosecutors.

Some said those involved were bent on battling police rather than protesting. To others, the violence seemed motivated by politics.

"The people are angry that the court cases against top officials keep getting delayed," said Ahmed Abdel Hamid, 26, a bakery employee who was at the scene overnight, referring to senior political figures from the discredited Mubarak era.

By early afternoon, eight ambulances were in Tahrir, epicentre of the revolt that toppled Mubarak on February 11, and the police had left the square. Dozens of adolescent boys, shirts tied around their heads, blocked traffic from entering Tahrir, using stones and scrap metal.

Some drove mopeds in circles around the square making skids and angering bystanders. "Thugs, thugs... The square is controlled by thugs," an old man chanted.

"I am here today because I heard about the violent treatment by the police of the protesters last night," said Magdy Ibrahim, 28, an accountant at Egypt's Banque du Caire.