Muhammad Bashar al-Faithi said a constitution written while an occupying army is in charge of the country will invariably be influenced by the aims of the occupation itself.
"Such a constitution will fulfill the aims of the occupation," he told Aljazeera.net.
The AMS position is that many Iraqis head to the polls unaware of the implications of their vote, he said, adding that religious and political coercion pushed many to vote.
Sunni participation in the 30 January vote was low, due to boycott calls, threats of violence or disaffection with the political process among a community struggling to come to terms with the loss of power.
Although the non-Kurdish Sunni community will be poorly represented in the National Assembly that is to draft the country's permanent constitution, all agree that its participation in the next political phase is crucial.
The AMS called on all Iraqis, Shia
and Sunni, to boycott the polls
However, al-Faithi rules out any AMS participation unless all occupying armies leave Iraq.
"A government born of these polls will be akin to a deformed child because it was not the product of fair and free elections," he said.
"It will have limited legitimacy and governance."
But al-Faithi played down any talk of a civil war, adding that conditions for such a conflict were far higher in the days immediately after the fall of Baghdad.
United Sunni front
On Friday, Iraq's leading religious Sunni authority called for the creation of an umbrella organisation of all Sunni groups and parties in a bid to unify the community's political position.
"We want to set up a general Sunni conference" comprising representatives from parties, tribes, unions, associations and provincial officials, said Shaikh Ahmad Abd al-Ghafur al-Samarrai during his sermon at Baghdad's Umm al-Qura mosque on Friday.
"This conference will not replace the various parties and associations but will be the link among all Sunnis," explained al-Samarrai, a senior member of AMS.
The clerical organisation represents about 3000 mosques across the country and has taken the lead in the search for a common Sunni stance after elections, which are expected to see the majority Shia and the Kurds come to power.