Jihadists have attacked an Iraqi army base west of Baghdad with six suicide bombers, killing 40 soldiers and capturing at least 70 others who fled.

Four suicide bombers detonated explosives-rigged armoured personnel carriers at the base in Saqlawiyah on Sunday, while two others attacked with explosive belts, General Rashid Fleih told AFP.

“Forty soldiers and officers were killed and contact was lost with between 70 and 80” who fled the base and were subsequently captured by the Islamic State (IS) jihadist group, Fleih said.

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IS militants, who led an offensive that overran swathes of the country in June, detonated a bridge five days ago in Al-Sijr, near the base, isolating it, he said.

The jihadists also planted bombs on roads leading to the area, making it even more difficult to send reinforcements and leaving the soldiers to fight the militants from inside the base.

Then the suicide bombers struck on Sunday in one of the deadliest single attacks on Iraqi soldiers in years.

Prime Minister Haidar al-Abadi has ordered that “the negligent brigade commanders” involved in the events in Saqlawiyah and Al-Sijr be detained and investigated, his office said.

The United States launched a campaign of air strikes against IS in Iraq last month and France has also bombed the group, which holds significant territory in neighbouring Syria and has declared a cross-border Islamic “caliphate”.

IS has executed hundreds of Iraqis and Syrians, beheaded foreign hostages and forced more than one million people from their homes in Iraq alone.