Late Saturday, a roadside bomb hit a civilian car on an open road about 200 kilometres (120 miles) north of Baghdad, police and a local official said.

When security forces arrived to the scene, jihadists opened fire on them.

The attack killed at least six Iraqi security personal and four civilians, including one who died of his wounds overnight, according to local medics.

There was no claim by IS but both the mayor and police blamed the group, which Iraq's government said it had defeated in late 2017.

That victory came after three years of brutal fighting to wrench back the one-third of Iraqi territory that had been captured by IS.

Although the jihadists no longer hold territory, sleeper cells wage hit-and-run attacks on state infrastructure, particularly in desert areas north of the capital.

Two weeks ago, 11 people were killed in an IS attack on a lookout post at Al-Radwaniyah on Baghdad's outskirts, areas which are predominantly Sunni Muslim.

The attacks have coincided with a new campaign by Iraq's security forces to arrest jihadists in hiding across the country -- but some say it has not been enough.

"Iraqi security forces just assured us this area had been cleaned," wrote Mashaan al-Jaboury, a Sunni MP representing Salahaddin, on Twitter late Saturday.

For Jamal al-Dhari, another Sunni figure writing on Twitter, the latest ambush "sheds light on the repeated failures in the fight against terrorism".

"The government of Mustafa al-Kadhemi must seriously put in placed a national strategy... and stop being satisfied with 'investigative committees,'" said Dhari.

Iraqis regularly mock their government for establishing investigative bodies that do not produce results.

The tensions come as the US-led coalition, which helped Iraq fight IS starting in 2014, is drawing down its troops.

This year, the US has already shrunk its contribution to the coalition from 5,200 to some 3,000 troops, as other countries have reduced their numbers as well.

The US announced last week it would withdraw another 500 troops by mid-January.