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Besieged Iraqi Refinery at Baiji 'Could Fall' to ISIS: U.S. Officials

The Iraqi government and Sunni militants traded competing claims about who controlled the huge refinery complex in Baiji.

Hours after Sunni militants attacked Iraq’s largest oil refinery Wednesday, U.S. officials told NBC News that the facility “could fall under ISIS control.”

The refinery complex outside the city of Baiji, about 130 miles north of Baghdad, would be a key prize for militants from the Islamic State of Iraq and al-Sham (ISIS) as they push south toward the capital.

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The Iraqi government and the militants made competing claims Wednesday about the situation in Baiji.

According to the Washington, D.C.-based Institute for the Study of War, the Iraqi government said Wednesday that its forces still controlled the refinery and that 40 militants were killed in the fighting. ISIS supporters said over social media Wednesday that militants took control of the refinery, but it’s not clear if the postings are accurate, analysts told NBC News.

U.S. officials said the refinery was “under siege” and “could fall under ISIS control.”

The attack helped to push the price of oil higher on Wednesday.

Iraqi counterterrorism forces battled militants at Baiji in sustained clashes Wednesday. Militants have held portions of the city since June 11, according to the military affairs website The Long War Journal, which tracks the insurgency in Iraq.

South of Baiji, Iraqi security forces fought militants Tuesday along the Samarra-Baghdad highway. The highway is mostly controlled by the Iraqi government but not secure, according to U.S. officials.

"The road between Samarra and Baghdad is the real crux of the fight," Bill Roggio, editor of The Long War Journal, said during a telephone interview with NBC News Wednesday.

Roggio said it's a priority for the Iraqi government to hold that highway in order to ward off further advances south by militants.

According to U.S. officials and to Iraq analysts based in New York, Washington and elsewhere in the United States, ISIS and other militant groups held firm control over a number of Iraqi cities on Wednesday, including Mosul, Tikrit, Fallujah, Tal Afar and Rawa. Militants partially held Baiji, Ramadi, Saadiyah, Jalawla, Al-Qa'im and Haditha.

Still other cities remained under government control but fighting was occurring there, including Baquba, Taji and Samarra, where there is a major Shiite shrine, the al-Askari Mosque, which was severely damaged in Sunni attacks in 2006 and 2007.

The Iraq analysts reached by NBC News rely on social media, news reports and contacts with government officials.

Analysts said Wednesday that militants hold a loose band of territory to the immediate west of Baghdad, as well as scattered cities north and northeast of the capital. The corresponding provinces are Anbar province to the west and Nineveh, Salahuddin and Diyala provinces to the north and northeast of Baghdad.

But analysts said the militants' march to Baghdad has been slowed in recent days by Iraqi security services.