The National Alliance for Supporting Legitimacy, a coalition supporting Egyptian ousted president Mohamed Morsi, announced Sunday that they will boycott the referendum on the draft constitution slated for January 14-15.
The new charter is "null" for being written by "the coup regime, " the alliance was quoted as saying by the Muslim Brotherhood's Freedom and Justice Party official website.
The statement said that 2012 constitution, masterminded mainly by Islamists, is still working, adding the protesters will continuously topple the current regime and restore Jan. 25 objectives in peaceful manner.
Egypt has been witnessing almost daily protests by loyalists of Morsi since the army removed him in July after mass protests against his rule.
Egyptian Interim President Adly Mansour called for a Yes vote for the referendum terming it as a move forward the country's transition to democracy. He invited the Islamists to join the national process and stop seeking illusions.
The new constitution is the most important step in a transition roadmap drawn up by the army on July 3 and should be completed with parliamentary and presidential elections next year.
The draft allows the authorities to switch the order of elections expected next year as the roadmap required parliamentary elections to be held first, but the new constitution would allow a presidential election first.
The Egyptian presidency held on Sunday its second session of the country's national dialogue over amending the transitional roadmap, official news agency MENA reported.
The president has not decided whether to start with presidential or parliamentary elections. During the session, the president has issued a decision to form fact-finding committee to investigate the events after June 30.
Since ouster of Morsi, the security forces has been launching wide-scale crackdown over the Islamists. Nearly 1,000 were killed during the protests and more than 2,000 including Morsi himself and Brotherhood top leaders were jailed over inciting violence and murder.
Pro-Morsi's alliance said in its statement on Sunday, that the political environment in Egypt of social division and hatred wasn' t suitable for amending the constitution, adding that the country didn't provide the guarantees for the integrity of the process from international supervision.
Most of the political parties including the ultra-Salafist Nour party, which defecting from Muslim Brotherhood and joined the future roadmap, backed the charter and called the people to vote with YES.
Other hardline movements, like the Jihadists deemed the new constitution is against the Sharia (Islamic rules), adding Egyptian to vote with YES are infidels, and their blood should be shed.
Meanwhile Al-Azhar, the most prestigious Sunni institution in the world, opposes such claims as weird views and that violates the Islamic rules. In its statement on Sunday, Azhar urged citizens to take part in the referendum to determine its destiny towards building a stable country.
The charter says in the preamble that "we are writing a constitution which ensures that the principles of Islamic Sharia are the main source of legislation."
The phrasing reverses previous Language added by Islamists in 2012 constitution that opened the door to wider interpretation of laws in line with religious jurisprudence.
Both critics and ultraconservative supporters of the charter said it had allowed stricter imposition on Islamic law.
Last week, the hardline Islamist group, al-Jamaa al-Islamiya, the main party after Muslim Brotherhood in the alliance, announced its boycott for the plebiscite, deeming that the amended version " confiscates the Islamic identity" and is "entrenched with savage secularism."
The group said on Monday that the Islamists will launch an active popular campaign to dissuade citizens from supporting the constitution and will distribute booklets to show the "weaknesses" of the new constitution.
It added boycotting the process won't contradict with protest peacefully outside referendum centers in January during the two voting days.
Experts raised concerns over participating in the process fearing violence by the Islamists, however Interim Prime Minister, Hazem al-Beblawi asserted on Sunday the country is keen to protect the voters, and called the citizens to participate even with No.
More than 200,000 army personnel and policemen will take part in securing the process.