Mohamed Morsi
Mohamed MorsiIsrael news photo: Flash 90

Egypt's top court said on Sunday it has begun an open-ended strike in what it called a "black day" for the judiciary after Islamist protesters blocked the courthouse ahead of a key ruling.

The Supreme Constitutional Court said it would "suspend work for an indefinite period... and until there is no more psychological and material pressure," in a statement carried by the official MENA news agency.

The move will be seen as an escalation in the standoff between the judiciary and President Mohamed Morsi who last week issued a decree expanding his powers and rendering his decisions immune from judicial oversight.

The court, which looks into the constitutionality of laws and is made up of 19 judges, was due on Sunday to examine the legality of an Islamist-dominated panel that drafted the new constitution.

AFP reported that hundreds of Morsi supporters had spent the night outside the courthouse, forcing judges to delay the potential scrapping of the panel.

In its statement, the court expressed its "utmost sorrow and pain" over the "moral assassination of its judges".

The new charter has become the focal point of Egypt's biggest political crisis since Morsi was elected in June, squaring Islamist forces against secular-leaning opponents.