Islamic State extremists unleashed a wave of suicide attacks targeting the Iraqi army in western Anbar province, killing at least 17 troops in a major blow to government efforts to dislodge the militants from the sprawling Sunni heartland, an Iraqi military spokesman said Wednesday.

The attacks came just hours after the Iraqi government announced the start of a widescale operation to recapture areas under the control of the Islamic State (ISIS) group in Anbar.

Brig. Gen Saad Maan Ibrahim, the spokesman for the Joint Military Command, told The Associated Press on Wednesday that the attacks took place outside the Islamic State-held city of Fallujah late the previous night.

The militants struck near a water control station and a lock system on a canal between Lake Tharthar and the Euphrates River where army forces have been deployed for the Anbar offensive, he said.

Ibrahim added that the Islamic State extremists used a sandstorm that engulfed most of Iraq on Tuesday night to launch the deadly wave of bombings. He said it was not clear how many suicide attackers were involved in the bombings but they hit the military from multiple directions.

Last month, the water station fell into the hands of ISIS militants — following attacks that also included multiple suicide bombings and that killed a general commanding the 1st Division and a dozen other officers and soldiers.

Iraqi government forces recaptured the station a few days later.

The Iraqi operation to retake Anbar, which is said to be backed by Shiite militias and Sunni pro-government fighters, is deemed critical in regaining momentum in the fight against the Islamic State.