Protests against the president's decision have continued in Cairo, while the Muslim Brotherhood is planning rallies backing him later.

Trading was suspended for 30 minutes as shares slumped in the first session since the president's announcement.

But the slide continued as soon as share dealing resumed.

Renewed clashes broke out in Cairo on Sunday morning between protesters and security forces in a street leading to Tahrir Square. Trails of tear gas could be seen in the square itself.

Stones were thrown close to the US embassy, but because concrete blocks had been erected in the area the situation was less tense than before, Mena news agency reported.

The barriers had been put up to secure key Egyptian government and parliamentary buildings, Mena added.

According to President Mursi's decree, announced on Thursday, no authority can revoke presidential decisions.

There is also a bar on judges dissolving the assembly which is drawing up a new constitution.

Mr Mursi sacked chief prosecutor Abdel Maguid Mahmoud, who was first appointed by ex-president Hosni Mubarak.

Mr Mahmoud's replacement, Talaat Ibrahim, has been given the job of re-examining all investigations into the deaths of protesters when Mr Mubarak was in power.

Egypt's judges denounced the decree on Saturday as an "unprecedented attack" on the judiciary, and the Judges' Club that represents them called for "the suspension of work in all courts and prosecution administrations".

Twenty-two rights groups signed an open letter which said the president "has dealt a lethal blow to the Egyptian judiciary" and demanded that the decree should be revoked immediately.

Opposition politician Mohamed ElBaradei had earlier complained that the president had "usurped all state powers and appointed himself Egypt's new pharaoh".

But the president's measures have also prompted his supporters to come out on to the streets and there were clashes on Saturday as pro-Mursi demonstrators tried to disrupt an emergency Judges Club meeting.

The Muslim Brotherhood, which backs Mr Mursi's Freedom and Justice Party (FJP) party, has called for further demonstrations in support of the decree after sunset.

The Islamist movement has called for a one-million-man march to be held at Abdin Square on Tuesday.