Egyptian President Mohamed Mursi has issued a decree that protects an assembly writing the country's new constitution from dissolution, and gives it extra time to finish its work.

The new constitution is a fundamental component of the transition to democracy in the Arab world's most populous nation.

Its drafting has been plagued by disputes, mainly pitting Islamists against their secular-minded critics.

The decree, read on state television by the spokesman for the elected Islamist president, stipulated that neither the assembly or the upper house of parliament, or Shura council, could be dissolved by the judiciary.

The decree also gave the constitutional assembly an additional two months to complete its work, meaning the drafting process could go on until February.

The constitution must be put to a popular referendum before it is approved. 

Once it is passed, Egypt is to hold elections to pick a new parliament. The previous assembly was dissolved in June.