BAGHDAD (Reuters) - Shi'ite cleric Moqtada al-Sadr has said he rejects the Iraqi constitution backed by his partners in the biggest parliament bloc, raising the possibility of a crisis over one of the country's most explosive issues.

"I reject this constitution which calls for sectarianism and there is nothing good in this constitution at all," he told Al Jazeera television late on Saturday.

Sadr criticised federalism in the constitution, which is rejected by Iraq's Sunni Arabs, who fear it will give Kurds and Shi'ites too much power and control over Iraq's oil resources.

"If there is a democratic government in Iraq, nobody has the right to call for the establishment of federalism anywhere in Iraq whether it is the south, north, middle or any other part of Iraq," he said.