"Two bombs exploded as the funeral procession was entering the cemetery" in Asdira, near the town of Sharqat, Salaheddin Shaalan told AFP.

Most of 14 people wounded in the blast were in "critical condition", he said.

Officials said the injured could not be transported to a hospital outside the village as night had fallen and inhabitants feared being ambushed by IS.

The funeral was for five members of the Hashed al-Shaabi paramilitary units, which fought alongside the army to expel the jihadist group from Iraqi towns last year.

They were killed on Wednesday night in a jihadist attack on a military convoy in the village, 250 kilometres (150 miles) north of Baghdad, a police official said.

The attack was the deadliest in Iraq since a January 16 double suicide bombing in Baghdad that cost 31 lives.

The Iraqi government declared victory over IS in December after pushing the jihadists out of their final holdouts along the border with Syria.

But the group retains the capacity to strike despite losing control of vast swathes of Iraqi territory it seized in 2014.

It still clings to pockets of desert in war-torn Syria and appears to be able to cross the porous border between the two neighbours.

Jihadists sometimes manage to snatch control of roads at night, especially in the Salaheddin province where Thursday's attack took place, and Anbar province along the border with Syria, security experts say.

On Sunday, four people were killed and several wounded in an IS suicide attack on the headquarters of a political party in Anbar.