Street clashes broke out on Monday as ousted Egyptian president Hosni Mubarak returned to court to face charges over the killing of protesters.
Mr Mubarak, 83, is the first Arab leader to stand trial in person since popular uprisings began sweeping the Middle East. He stands accused of authorising the use of live ammunition to quell protests, of corruption and abuse of power.
A helicopter landed near the Cairo court and shortly afterwards the ailing Mr Mubarak was wheeled on a gurney into the courtroom's steel cage for the second session of his trial, Reuters reports.
Hundreds of riot police stood guard but clashes erupted between a crowd of Mubarak supporters outside the building and a group demanding justice for those killed in the uprising that toppled him six months ago.
The pro-Mubarak crowd threw stones, the police cordon dividing them broke and the Mubarak supporters chased their opponents away from the court building.
In a courtroom packed with lawyers, Mr Mubarak looked composed and stern, hands clasped over his chest. An intravenous needle was implanted in his left hand.
He exchanged a few words with his sons Alaa and Gamal, also on trial and in the same cage with their father.
The hearing could decide if the head of the ruling military council will take the stand as a witness.