The first attack took place late in the day near Tharthar Lake southwest of Samarra, a longtime stronghold of Sunni jihadist groups some 100 kilometres (65 miles) north of Baghdad.

The blast killed seven fighters and wounded three, the army said, adding it was carried out by "a suicide terrorist" -- its standard term for Islamic State group jihadists.

Later, a second attacker blew up a car packed with explosives at the same site, killing another four fighters, the army said.

No group immediately claimed responsibility.

Sadr's Saraya al-Salam (Peace Brigades) force took part in the gruelling Iraqi operation against IS after the jihadists seized a third of Iraq and swathes of neighbouring Syria in 2014.

In late 2017, Iraq declared victory over the jihadist group, but its sleeper cells continue to carry out attacks across the country