Suspected Islamic State group members planted the bomb in a pickup left outside the restaurant by an important highway in Hajjaj, a police officer told AFP on condition of anonymity.

"Five people were killed and 32 wounded," in the bombing near Tikrit city, 175 kilometres (108 miles) north of Baghdad, the officer said.

The attack took place during lunchtime and targeted "a restaurant where there were travellers returning from Baghdad to Dahuk" in Iraqi Kurdistan to the north, the police officer said.

Medical sources said women and children were among those wounded, while confirming five people were killed.

The restaurant had already been attacked by two suicide bombers in the spring, the police officer said.

On Monday, security forces said they had killed 13 jihadists north of Tikrit as part of a large-scale land and air operation against extremists in Iraq's desert and mountainous areas.

Although Baghdad declared victory over IS in December, members of the jihadist group continue to carry out deadly attacks.

On Tuesday a suicide bomber killed a member of the security forces and injured four others in Anbar province, a western desert area, a security official said.

That attack came a day after jihadists killed four people in Khanaqin north-east of Baghdad, including two Kurdish fighters who were on leave, according to a Kurdish political official in the area.

"IS jihadists kidnapped six people. Two were freed and four others were beheaded," the official said on condition of anonymity.