Egypt's interim President Adly Mansour is expected to announce the date of a referendum on the amended 2012 constitution in a statement on Saturday, Egypt's state news agency MENA reported on Wednesday.

The website said the announcement will be made in the presence of the 50 members of the committee who amended the charter as well as top state officials including Prime Minister Hazem El-Beblawy, his cabinet, members of the Supreme Judicial Council, and representatives of Al-Azhar and the Coptic Church.

Presidential spokesman Ihab Badawy said the referendum would be the first major step in Egypt's transitional roadmap.

The roadmap began after the ouster of Islamist president Mohamed Morsi by the army and Morsi's opposition. It also includes parliamentary and presidential elections.

The Muslim Brotherhood, the group from which Morsi hails, did not issue a statement regarding their participation in the constitutional committee, but they are expected to either boycott or reject the charter.

The Salafist Islamist party Nour, who took part in drafting the amendments, urged voters to accept the charter.

Other parties and groups in Egypt are still in the process of formulating a stance from the referendum, but so far some groups, such as the Strong Egypt party led by ex-Muslim Brother Abdel-Moneim Abul-Fotouh and the 6 April Youth Movement urged a 'No' vote, accusing the charter of not fulfilling revolutionary goals.

Egypt's Administrative Development Minister Hany Mahmoud said on Monday the referendum will be held mid-January and carried out in two stages.