Suicide bombers killed seven people and wounded 12 in an attack on a power plant north of Baghdad on Saturday, an Iraqi security official said.

Armed with grenades and wearing explosives belts, three attackers entered the facility in Samarra, about 100 kilometres north of the capital, at 2am (local time), the official told AFP.

“They attacked the plant's workers, killing seven and wounding 12, according to an initial assessment,” said the official, who spoke on condition of anonymity.

Security reinforcements then arrived on the scene, killing two of the bombers and evacuating the employees.

The attack comes as Iraq marks the first day of the Eidul Azha feast.

There was no immediate claim of responsibility for the attack, but the militant Islamic State (IS) group frequently carries out suicide bombings in Iraq.

In 2014, IS captured almost a third of Iraqi territory in a lightning offensive. It now only holds two pockets of territory in the country.