The Syrian Democratic Forces (SDF) handed them over at the Rabia border post, Iraq's joint operations command said in a statement.

It said the captives would be questioned by the interior ministry's intelligence services, which would take "all necessary judicial measures".

Iraq has prosecuted thousands of its nationals on the accusation of IS membership, a charge which carries the death sentence under its anti-terrorist laws.

The SDF has warned of the high security risks of holding thousands of IS prisoners, as highlighted by a jihadist jail break attempt in January in Ghwayran, northeast Syria, that cost hundreds of lives in several days of clashes.

Iraq also repatriated 100 jihadists in December, the latest in a string of such operations.

A senior military official told AFP that some 3,500 Iraqi detainees remain in Syrian Kurdish jails, as well as 30,000 other Iraqis, including 20,000 children, in Syria's Al-Hol camp for the displaced.

In contrast to the reticence of Western countries, Iraq has so far repatriated more than 450 families from the camp.

Iraq announced victory against IS in late 2017 after three years of ferocious fighting backed by paramilitary forces and the US-led air coalition.

But IS cells still carry out hit-and-run attacks, particularly in vast desert regions of northern and western Iraq near the porous border with Syria.

The IS group has "maintained the ability to launch attacks at a steady rate in Iraq, including hit-and-run operations, ambushes and roadside bombs", a UN report said in January.

It said the jihadist group still has "between 6,000 and 10,000 fighters across both countries (Iraq and Syria), where it is forming cells and training operatives to launch attacks".