As a result, the election could be delayed.
“The third article in the Presidential Decree Law number 202 for 2014 on dividing constituencies in the parliamentary elections is unconstitutional in its application on individual seat voting,” said judge Anwar al-Asy.
Egypt has been without a parliament since June 2012 when a court dissolved the democratically elected main chamber, reversing a major accomplishment of the 2011 uprising that toppled autocrat Hosni Mubarak.
The Administrative Court is due to meet later this month to rule on whether the election will be delayed, judicial sources said.
“It will be repeated after drafting a new law which will be proposed to the President through the State Council in the legislative department after being ordered by the Cabinet. The new law will be proposed to the President for issuance,” said claimant lawyer, Mohamed Yehia Albeltagy.
The parliamentary election is the final step in a political roadmap the army announced in July 2013 after ousting Islamist Mohamed Mursi, Egypt's first democratically elected president, following mass protests against his troubled year in office.
Egyptian leaders say the election shows their commitment to democracy but critics say President Abdel Fattah al-Sisi, who as army chief toppled Mursi, has undermined freedoms gained after the uprising that ended Mubarak's 30-year rule.
“The president issued directives to the government to quickly make the necessary legislative changes to the laws organizing the election process,” a statement from the presidency said.
In the absence of parliament, Sisi has wielded legislative authority to introduce economic reforms that have impressed investors, while also curtailing political freedoms.