Jihadist suicide attackers broke into a gas plant north of Baghdad on Sunday, killing at least seven people and setting fire to gas tanks, officials said.
The Islamic State (IS) group claimed responsibility for the attack on the Taji plant, which lies about 20 kilometres (12 miles) north of the capital.
Interior ministry spokesman Saad Maan said eight attackers broke into the gas plant at dawn and blew up a car bomb at one of its entrances.
Some of the attackers detonated suicide belts while others were killed by bullets, according to Maan, who said explosions set fire to three gas tanks.
Huge plumes of black smoke billowed into the sky but the fire was quickly brought under control.
The attack killed at least seven people and wounded at least 22, according to security and medical officials.
In an online statement, the Islamic State group said the attack was carried out by four suicide bombers, for whom it provided noms de guerre.
"They killed the guards at the gate before raiding the headquarters and killing all inside," the statement said.When additional Iraqi forces massed at the gate for an attack, "our brothers detonated a car bomb in the middle of their gathering," it went on, saying that the militants clashed with security forces and detonated explosive belts among them.
The jihadist group estimated the number of dead and wounded at 45.
IS has been steadily losing ground to the Iraqi security forces in recent months.
According to the government, IS controls only 14 percent of Iraqi territory, down from the 40 percent it held in 2014.
But the group has intensified its attacks behind the front lines, detonating car bombs in civilian areas and infiltrating sensitive sites with suicide commandos.
"Daesh (IS) is turning to targeting civilian facilities in cities after losing the battle on the front," said Colonel Mohamed al-Bidhani, of the government's "war media cell".
On Saturday, a group of IS fighters snuck into Amriyat al-Fallujah, a government-held town west of Baghdad, in a similar suicide raid that killed five people.
The group also claimed responsibility for a spate of bombings in Baghdad on Wednesday that killed close to 100 people, the bloodiest day in the Iraqi capital this year.