Egypt's highest security body has warned that the search for a peaceful end to a standoff over sit-ins by supporters of the ousted president is not open-ended.

The National Defense Council, which is led by the interim president and includes top ministers, met late on Saturday and issued a statement on Sunday.

The statement said that any negotiated end to the sit-ins by Mohammed Morsi supporters would not spare what it called "law-breakers" and others who incite against the state.

Morsi's supporters are camped in two Cairo squares demanding his reinstatement.