Insurgents killed one engineer and detonated several explosive devices during a weekend attack at the Baiji oil refinery. The refinery is the largest in Iraq and the explosion removed about 150,000 barrels per day from the market, The New York Times reports.
Abud al-Kadir Salih, an official working in the Iraqi Oil Ministry, told the Times the disruption would create a crisis.
"It will affect consumers of fuel from factories to power plants and people in daily need," he was quoted as saying. "It will be very hard to cover the shortfall."
Iraqi officials blamed al-Qaida for the attack, saying it was part of a plan to undermine economic development in the country.
The disruption followed protests in Iraq last week. Iraqi Prime Minister Nouri al-Maliki called on Iraqis to avoid demonstrations scheduled for Friday, saying militants would try to exploit the situation.