The political groups had earlier agreed that Islamic representatives would constitute 50 per cent of the committee.
The sources said the disagreement is over whether the seats for Al-Azhar and the moderate Islamist Wasat Party should be considered civilian or Islamic representation, particularly because considering them civilian would raise the number of seats allocated Islamic-oriented members to 57 per cent of the total.
Political parties and groups on Thursday had agreed on the representation of different factions after the Supreme Council of the Armed Forces gave them 48 hours to agree on the Constituent Assembly formation.
The Thursday deal equally split the assembly into Islamist and non-Islamist representatives.
The old formation, which had been annulled by an administrative court verdict, was dominated by Islamists.
