Founder of the liberal Dostour Party Mohamed ElBaradei commented on the referendum in light of the current political situation.
"In the presence of an immune president with absolute powers and the lack of judicial authority and a draft constitution which establishes tyranny, resorting to the ballot box is a farce devoid of legitimacy and reflects false democracy", the former director of the International Atomic Energy Agency posted on his Twitter account on Monday.
Mursi issued a decree two weeks ago expanding his powers and shielding his decisions from judicial review. A move considered as a "a coup against democracy and legitimacy" by political forces.
According to Egyptian judges it was seen as an attempt to undermine their role and disregard the country's constitution which pushed them to suspend their work in protest.
An Islamist-led assembly finished drafting a controversial charter on Friday allowing it to be put to referendum on December 15.
Liberal, leftist and socialist forces rejected that decision saying that putting the charter to a referendum without political consensus is "an insistence on dividing society".