The Islamic State of Iraq and the Levant (ISIL) group has reportedly carried out a series of suicide attacks on military convoys northeast and southeast of the city of Fallujah, killing at least 55 people, Al Jazeera has learnt.

Three blasts on Tuesday struck army convoys travelling in Anbar province to take part in a planned offensive aimed at retaking the provincial city of Ramadi from ISIL, Al Jazeera's Imran Khan, reporting from Baghdad, said.

He said that the attacks were a "very big blow" to the military.

ISIL has routinely used car bomb attacks to a "devastating effect" against Iraqi forces, he added.

"Car bombs have proven to be a very big problem for the Iraqi security forces," he said, noting that the tactic played a major part in the capture of Ramadi.

Brigadier General Saad Maan Ibrahim, the spokesman for the Joint Military Command, gave a lower death toll. He told The Associated Press that 17 troops were killed in the attacks.

The bombings came as Iraqi forces prepare for a massive bid to retake the capital of mainly Sunni Muslim province.

Thousands of troops and allied Shia militiamen have been deployed to the area to retake territory seized by ISIL since last year.