The appointment of leading liberal politician Mohamed ElBaradei as Egypt's interim prime minister has hit a snag, as officials fight to restore calm after deadly Islamist protests swept the country.

State media had said the 71-year-old Nobel Peace Prize winner had been appointed and would be sworn in within days.

The announcement came three days after the army removed Islamist leader Mohammed Morsi from power.

But a presidency spokesman now says opposition to Mr ElBaradei being named as interim leader must be taken into account.

The spokesman says there are several options for prime minister and there is no date to appoint someone to the role.

The country apparently changed its tune after Egypt's second biggest Islamist group, the Nour Party, opposed Mr ElBaradei's nomination.

Nour had backed a military-led political roadmap to guide the country to new elections, but said it would withdraw from the transition process if Mr ElBaradei was confirmed as prime minister.

Losing Nour's backing would significantly weaken the position of the military.

A youth activist who met interim head of state Adli Mansour says the two issues are linked.

The confusion comes amid continuing tensions in the country.

Sorry, this video has expired Morsi supporters in deadly clashes with opposition protesters

Tens of thousands of Mr Morsi's supporters have vowed to continue protesting, raising the prospect of further violence that has thrown the country into fresh turmoil.

Clashes between Mr Morsi's supporters and opponents yesterday left more than 30 people dead and hundreds wounded.

The Islamists accuse the military of conducting a brazen coup against Mr Morsi, Egypt's first democratically elected president, after millions called for his ouster on the June 30 anniversary of his first turbulent year in power.

The level of violence has dropped but hospital wards in various parts of the country are filled with the injured: some from gunshot wounds, others hurt in rock and firebomb attacks.

Mubarak pleads not guilty

Amid the unrest, lawyers for Egypt's ex-president Hosni Mubarak entered a not guilty plea when his retrial for alleged complicity in the killings of protesters in 2011 resumed.

Mubarak and seven top security chiefs are charged with incitement in the killings of protesters who rose up against him in early 2011.

Along with his two sons, Mubarak is also charged with corruption.

The 85-year-old former strongman appeared in the dock behind bars on Saturday, wearing dark sunglasses and a white prison uniform.

During the televised hearing, Cairo's criminal court heard submissions by the defence before adjourning proceedings until August 17.

At the previous hearing, on June 10, cartons filled with police notebooks and videos of demonstrations on Cairo's Tahrir Square, epicentre of the 2011 revolt during which almost 850 people died, were submitted to the court.

The original trial last year on charges of complicity in killing demonstrators led to a life sentence for Mubarak and former interior minister Habib al-Adly, but an appeals court ordered a retrial, citing procedural errors.

ABC/wires