"Ten days ago we started to set up a barbed wire security fence with surveillance towers along the border with Syria," said Anwar Hamid Nayef, spokesman in Iraq's Anbar province.

The frontier barrier includes a six-metre-wide trench and involves thermal cameras and drones scanning the border for jihadists attempting to cross from Syria.

Baghdad declared victory over IS at the end of last year, but the group holds pockets of territory in the vast deserts of eastern Syria and maintains its ability to strike inside Iraq.

The new fence so far runs for 20 kilometres (12 miles) north from the area around the border town of Al-Qaim, which Iraqi forces retook from IS in November.

In total the frontier stretches for some 600 kilometres.

Border spokesman Nayef said that experts from Baghdad's ministry of defence and an anti-IS coalition spearheaded by the United States would come "to evaluate the effectiveness of the fence".

"If they approve the installations, we will continue along the whole border with Syria," he said.

In a sign of the continuing menace it poses to Iraq, the bodies of eight captives executed by IS were this week found along a highway north of Baghdad.

In a bid to combat the jihadists, Iraqi forces have carried out a series of air strikes against IS inside Syria.