SAMARRA, Iraq: A blast killed eight members of the security forces on Wednesday during an operation in northern Iraq to detonate explosives planted by the Islamic State group, a security source said.

A military sapper was preparing a charge to detonate unexploded ordnance laid by the militants in Salaheddin province "when a mistake was made and the explosion happened", the source told AFP.

The blast killed six soldiers and two policemen charged with oil field protection, the source said.

Some of Iraq's largest oil refineries are situated in the region where the explosion occurred. IS took the area in 2014 and it was recaptured by the Iraqi army in 2016.

In 2017 Baghdad announced victory over the militant group, and attacks in Iraqi cities have since become much rarer, although troops continue to fight IS sleeper cells in mountainous and desert areas.

The militants still mount deadly operations, mostly at night and in remote areas.

On July 19, the IS said it was behind a bombing that killed more than 30 people at a market in the Baghdad district of Sadr City, a densely populated Shiite stronghold.