Beirut (AFP) - Al-Qaeda's Syrian affiliate and its Islamist allies launched an attack Wednesday on the last two Shiite Muslim villages under regime control in northwest Idlib province, militants and a monitor said.

The "Army of Conquest" rebel coalition, which includes Al-Qaeda branch Al-Nusra Front, announced online its assault on the villages of Fuaa and Kafraya.

"We decided to begin the 'Battle of Kafraya and Fuaa' against the forces of (Bashar al-) Assad and Iranian militias", a statement read.

Rami Abdel Rahman, head of the Syrian Observatory for Human Rights, said the villages are the last two Shiite Muslim localities held by the regime in Idlib, which rebels have overrun in recent months.

"This is a very violent attack. There is heavy shelling on the towns, which have been besieged since March," he told AFP.

The Army of Conquest said it decided to launch its attack after the regime and Lebanese Shiite movement Hezbollah began an offensive on Zabadani, the last rebel-held bastion along Syria's border with Lebanon, earlier this month.

It said the attack would "give you a taste in the north of what our people are tasting in Zabadani".

Hezbollah, which is supported by Iran, had stationed commanders in Kafraya and Fuaa and had trained local military leaders, Abdel Rahman said.

The Army of Conquest seized Idlib city on March 28 and went on to capture a major town and the province's largest military base.

Idlib province lies adjacent to the regime's coastal bastion of Latakia, the heartland for Alawites -- the offshoot of Shiite Islam from which the Assad clan hails.