At least 17 Iraqi soldiers have been killed in a series of suicide attacks by Islamic State (IS) militants in Anbar province, security officials say.
The militants reportedly launched a wave of bombings outside the IS-held city of Falluja on Tuesday night.
The attacks came hours after pro-government forces began an operation to drive the jihadists out of Anbar.
On Wednesday, troops and militiamen were said to have taken up positions south of the provincial capital Ramadi.
The city was captured two weeks ago after troops withdrew despite vastly outnumbering the IS forces attacking, prompting the US defence secretary to question their “will to fight”.
A source in the Iraqi army’s 1st Division told the BBC that 17 of its soldiers were killed in an attack on its headquarters 5km (3 miles) east of Falluja that involved three suicide car bombs.
The source added that suicide car bombs and militants wearing explosive vests were also used to attack troops and Shia militiamen north of the town of Karma, also east of Falluja.
In both cases, the militants took advantage of a sandstorm that engulfed most of Iraq on Tuesday night to get close to their targets.
Read more: BBC