A top Egyptian security official says that authorities will deal "firmly" with any attempt to disrupt a referendum on the country's amended constitution, a warning directed at followers of the ousted Islamist president who have been staging regular protests since his overthrow.

Chief of General Security Gen. Sayyed Shafiq said Wednesday that the security forces were setting up a plan for the vote, set to be held within a month. "Any attempt to disrupt the referendum on the constitution will be faced with firmness and decisiveness according to the law," he said.

Supporters of Mohammed Morsi have denounced the vote as a "rubber stamp" for the political order set up after his overthrow.

Two secular-leaning panels spent three months rewriting the 2012 constitution drafted under Morsi.