"Mubarak has left Sharm el-Sheikh hospital," Mohamed Naguib, head of security in South Sinai, told Reuters after a motorcade that included ambulances and security vehicles left the hospital in the Red Sea resort, headed for the local airport.
Speculation had swirled until hours before the start of the trial about whether the 83-year-old, hospitalised in the Red Sea resort since April, would turn up to face charges of conspiring over the killing of demonstrators.
Mr Mubarak's trial is unprecedented. He was forced out of office by his people and is being held to account. Tunisian President Zine al-Abidine Ben Ali, the first Arab leader to be ousted in the Arab Spring, was tried in absentia and is in Saudi Arabia.
Police patrolled the street near Mr Mubarak's hospital and barred the way to a small group of protesters outside, chanting: "The people want the execution of the killer."
In Cairo, the court, with a cage for defendants, has been set up at the Police Academy, with a screen erected outside the building to show the trial
A small pro-Mubarak rally chanted: "Oh Mubarak hold your head high" and "We will demolish the prison and burn it down, if Hosni Mubarak is sentenced." Another small group against Mr Mubarak called out: "Raise your voice, Freedom will not die."
Medical sources said members of Mubarak's family had arrived at his hospital late on Tuesday, and an airport source said a medically equipped aircraft had landed at the local airport.
Many protesters are determined to see him in the dock and are likely to be enraged if he does not appear. Security was tightened in Cairo's Tahrir Square. Police and military officers in riot gear stood there, with dozens of police trucks and a few army armoured personnel trucks.
Many Egyptians see his illness as a ploy so ruling generals can avoid publicly humiliating the war veteran and ex-president who ran Egypt, the Arab world's most populous nation, for 30 years until he was driven out on Feb. 11.
If convicted, Mr Mubarak could face the death penalty. In his only public comments since stepping down, he vowed in April to clear his name and that of his family of accusations of corruption.
