Iraqi security forces on June 19 battled Sunni insurgents for control of the country's largest refinery in Baiji, some 200 kilometers north of Baghdad.
Officials say security forces loyal to Prime Minister Nuri al-Maliki's Shi'ite-led government retain control of the refinery but that clashes with insurgents from Al-Qaeda offshoot ISIL are ongoing.
Video aired by Al-Arabiya television, however, showed smoke billowing from the plant and a black flag used by ISIL flying from a building.
Baiji lies in territory captured in the past week by ISIL-led Sunni insurgents, who took control of Iraqi's second-largest city, Mosul, and the city of Tikrit.
The Iraqi government, meanwhile, is awaiting a U.S. response to an appeal for air strikes against the militants.
President Barack Obama met with top lawmakers at the White House on June 18 to discuss possible U.S. military action in Iraq, amid questions over whether congressional approval would be requested or even needed.
Obama met with Senate Majority Leader Harry Reid (Democrat-Nevada), Senate Minority Leader Mitch McConnell (Republican-Kentucky), Speaker of the House John Boehner (Republican-Ohio), and House Minority Leader Nancy Pelosi (Democrat-California) for more than an hour.
Speaking to reporters afterward, McConnell said Obama "indicated he didn't feel he had any need for authority from us for steps that he might take."
Pelosi said after the meeting that Obama does not need "any further legislative authority" to pursue security assistance for Iraq, without specifying what options were discussed.
Possible Air Strikes
However, "The New York Times" quotes White House officials and Democratic aides as saying Obama has not ruled out the possibility of coming to Congress for a vote.
Washington is reported to be considering air strikes or drone attacks in response to an Iraqi call for military help, but has ruled out combat troops.
Speaking before the Senate on June 18, U.S. Senator John McCain (Republican-Arizona) argued in favor of air strikes in response to an Iraqi call for military help.
"There is a need for immediate action," said McCain.
Obama has already announced that some 275 U.S. soldiers have been sent to protect the American Embassy in Baghdad.
WATCH: Lines Grow As Fuel Runs Short In Iraq's Kirkuk
Shortly before his meeting with Obama, Boehner said he "absolutely" opposes working with Iran to help Iraq's Shi'ite-led government combat the insurgents.
"I can just imagine what our friends in the region, our allies, would be thinking by reaching out to Iran at a time when they continue to pay for terrorism and foster terrorism," he said.
Meanwhile, U.S. Secretary of State John Kerry said on June 19 that the United States is "interested in communicating with Iran" to share information about the ISIL insurgency.
But Kerry, speaking on the U.S. television network NBC, said Washington is not seeking to work together with Iran to address the crisis.
Asked about the possibility of U.S. air strikes, Kerry also said that "nothing is off the table" and that "all options" are still available to Obama.
With reporting by AP, AFP, Reuters, and "The New York Times"