The United States has called for calm in Egypt, where there are fresh protests over President Mohamed Morsi's assumption of sweeping powers.
'The decisions and declarations announced on November 22 raise concerns for many Egyptians and for the international community,' said State Department spokeswoman Victoria Nuland, in a statement on Friday.
'One of the aspirations of the revolution was to ensure that power would not be overly concentrated in the hands of any one person or institution,' she said, referring to the uprising that toppled veteran ruler Hosni Mubarak.
Nuland warned that Egypt's 'constitutional vacuum ... can only be resolved by the adoption of a constitution that includes checks and balances, and respects fundamental freedoms, individual rights, and the rule of law consistent with Egypt's international commitments'.
'We call for calm and encourage all parties to work together and call for all Egyptians to resolve their differences over these important issues peacefully and through democratic dialogue,' she said.
On Thursday, Morsi undercut a hostile judiciary that had been considering whether to scrap an Islamist-led panel drawing up a new constitution, stripping judges of the right to rule on the case or to challenge his decrees.
The decision effectively placed Morsi's presidency above judicial oversight until a new constitution is ratified.
But the president insisted Egypt was on the path to 'freedom and democracy'.
'Political stability, social stability and economic stability are what I want and that is what I am working for,' he told an Islamist rally outside the presidential palace.
'I have always been, and still am, and will always be, God willing, with the pulse of the people, what the people want, with clear legitimacy.'
Earlier, MENA news agency quoted him as saying: 'No one can stop our march forward ... I am performing my duty to please God and the nation and I take decisions after I consult with everyone'.
State media reported protesters had torched Muslim Brotherhood offices on Friday.
The offices of the Freedom and Justice Party (FJP), the Muslim Brotherhood's political arm, were set ablaze in the canal cities of Ismailiya and Port Said, it was reported.
An FJP official told AFP the party's office was also stormed in the Mediterranean city of Alexandria, where clashes broke out between rival demonstrators.
In Cairo, an array of liberal and secular groups, including activists at the forefront of the protest movement that forced veteran strongman Hosni Mubarak from power early last year, marched on Tahrir Square, Cairo's iconic protest hub, to demonstrate against the 'new pharaoh'.
Morsi's backers led by the powerful Muslim Brotherhood gathered outside the presidential palace in north Cairo in a show of support for his decision to temporarily place his decisions above judicial oversight.
'The people support the president's decisions,' the crowd chanted.