TIKRIT, Iraq (Reuters) - A rocket hit a small oil refinery in northern Iraq on Sunday, causing a fire at a fuel storage tank and forcing a complete shutdown of operations after the blaze spread to a nearby pipeline network, two refinery officials said. Islamic State claimed responsibility for attacking the Siniya refinery, in a statement posted on the group’s official channel. It said two Katyusha rockets were used in the attack. It gave no further details on any casualties. A spokesman for the state-run Northern Refineries Co, which manages a number of Iraqi refineries, earlier told Iraq’s state news agency that two rockets had hit the Siniya refinery, causing a fire that it said had been controlled. Officials said halting operations at the Siniya refinery, which has refining capacity of 30,000 barrels per day, was a safety measure to prevent further damage. “We completely shut down production units to avoid extensive damage that could result,” a chief engineer at the refinery said, speaking on condition of anonymity. An oil ministry statement said firefighters managed to put out the fire at a fuel tank and cited Deputy Oil Minister Hamid Younis as saying that operations are expected to be resumed in “the next few hours after assessing the damage”. Sunday’s attack signals that Islamic State militants are still capable of launching attacks against security forces and vital energy sites, despite being defeated during a 2014-2017 U.S.-backed military campaign. There were no reports of casualties at the facility, which is near Iraq’s largest oil refinery of Baiji in the Northern Salahuddin province.