SAMARRA: An attack on a major Iraqi oil refinery early on Saturday left two engineers dead and one of its refining units badly damaged, prompting the facility to shut down, a senior official said.

The attack on the Baiji refinery, in Salaheddin province north of Baghdad, struck at around 4:30 am (0130 GMT) when gunmen stormed the installation, killed the engineers and planted bombs at the refining unit.

"Armed men entered the refinery and shot dead two of the engineers," Abdul Qader al Saab, the facility's deputy chief.

"Then they detonated bombs at one unit, the Al Shamal unit, of the refinery, which represents 25 percent of the refinery's production. In the morning, we came to put out the fire, which erupted as a result of the bombs."

He added that the unit was badly damaged.