A health ministry official in Egypt says 29 people have been killed in clashes between security forces and anti-government protesters nationwide on the anniversary of the country's 2011 uprising.

Khaled el-Khateeb said Saturday most of those killed were in Cairo. Fierce clashes have raged between largely Islamist protesters and security forces in eastern Cairo. There were at least three killed in Alexandria and the southern province of Minya.

Saturday marked the anniversary of the start of the 2011 uprising that forced longtime autocrat Hosni Mubarak to step down. It was marked by rival rallies of those supporting the military-backed government and supporters of Mubarak's successor, Islamist President Mohammed Morsi.

Morsi was removed from office in July following mass protests against him.

In the northern Sinai peninsula, five soldiers were killed as an Egyptian military helicopter crashed after being fired on, locals said. Egyptian army spokesman Ahmad Ali confirmed the crash near the village of al-Kharruba and the deaths of the soldiers, but did not provide further details about the incident.

He said a search was underway for the helicopter's crew. Locals said they saw gunmen in a pickup truck hit the helicopter with a missile.