Sunni-led militants have declared an Islamist state in part of northwestern Iraq and have threatened to push south into the predominately Shiite areas of the country.

Iraqi Oil Minister Abdul Karim Luaibi said the government was dedicated to supplying the ideal safe environment for international companies working in Iraq.

"Work in oil refining facilities and oil fields is normal and the ministry has supplied the extra protection needed for those locations by coordinating with security authorities and energy officials," he said in a statement.

The U.S. Energy Information Administration said violence in Iraq has not reduced the availability of Iraqi oil on the global export market. Nevertheless, EIA said there was a degree of uncertainty in the Iraqi oil sector because of the Sunni insurgency.

EIA said it reduced its production growth forecast from Iraq by 300,000 barrels per day.

Southern Iraq produces around 2.8 million bpd and the semiautonomous Kurdish north produces about 200,000 bpd.