BEIRUT — A group of extremist Islamist factions in Syria has rejected the country's new opposition coalition, saying in a video statement they have formed an "Islamic state" in the embattled city of Aleppo to underline that they want nothing to do with the Western-backed bloc.

The video appears to be a reaction to the Syrian National Coalition for Opposition and Revolutionary Forces, formed Nov. 11 in Qatar to unify groups trying to topple the regime of President Bashar Assad. The coalition is led by a popular Muslim cleric and is seen as a way to counter the growing influence of Islamic extremists in the 20-month old rebellion that has claimed more than 36,000 lives.

The statement by 13 radical factions that was posted on a militant website late Sunday suggested the extremist elements — including the al-Qaida-inspired Jabhat al-Nusra — are suspicious of the new coalition. They rejected what they said was a "foreign project" and declared the northern city of Aleppo, where many radical groups have been fighting, an "Islamic state."