Egypt's Administrative Court issued on Tuesday a ruling halting the parliamentary elections which were due to begin later this month.
The ruling is based on another ruling issued on Sunday by the Supreme Constitutional Court deeming an article in the constituency law, drafted to regulate the elections, unconstitutional.
The legislation was issued in December and was one of the last steps that needed to be taken before elections could be held.
Lawyer Ibrahim Fekri who filed the legal challenge to the law said it was characterised by lack of equality among voters.
Shortly after the court's decison, President Abdel Fattah al-Sisi ordered the government to amend the law and to take the necessary legal procedures to avoid a delay to holding elections.
The parliamentary elections would mark the final step in a road map announced by President Abdel Fattah al-Sisi in July 2013, after the ouster of Islamist President Mohamed Mursi following mass protests against his rule.