Shiite clerics called on Iraqi civilians to take up arms against advancing Sunni insurgents inspired by al-Qaeda, drawing the battle lines for a major sectarian confrontation in the fracturing state.

Shiite clerics called on Iraqi civilians to take up arms against advancing Sunni insurgents inspired by al-Qaeda, drawing the battle lines for a major sectarian confrontation in the fracturing state.

Shiite clerics called on Iraqi civilians to take up arms against advancing Sunni insurgents inspired by al-Qaeda, drawing the battle lines for a major sectarian confrontation in the fracturing state.

The Iraqi government expressed frustration Thursday over U.S. reluctance to launch airstrikes against al-Qaeda-inspired insurgents, pleading for American assistance as the militants battled for control of Iraq’s biggest oil refinery.

Amid conflicting reports on the fate of the Baiji oil refinery, Hussein al-Shatub, a provincial council member for Salahuddin province, told Iraq's Radio Sawa that the facility fell to insurgents from the Islamic State of Iraq and Syria (ISIS) on Thursday. He said a deal was struck with the militants to ensure the safe evacuation of about 300 workers at the facility.

A government spokesman in Baghdad, Ali al-Musawi, confirmed the evacuation but insisted that the refinery remained under government control. Iraqi officials maintain that security forces have repelled insurgent attacks on the facility.

The Associated Press reported that the black flag of ISIS was flying over the refinery Thursday.

In a televised address Thursday, an Iraqi military spokesman, Gen. Qassim Atta, said 70 militants were killed in the attack on the Baiji refinery. He also claimed that government forces on Thursday recaptured areas of Tal Afar, a religiously mixed town west of the rebel-held northern city of Mosul, and were carrying out airstrikes on other neighborhoods.

Abdullah Jabbouri, a tribal leader in Baiji, said his men were assisting the government in repelling ISIS attacks on the refinery.

“Our forces are holding out, and their spirits are high,” he said. “This facility belongs to the state, and it’s critical we defend it.”

The loss of the refinery would mark another strategic blow to Iraqi Prime Minister Nouri al-Maliki, whom the United States is pushing to find a political solution to the Iraq crisis that threatens to engulf the entire Middle East. Maliki’s top priority, however, is U.S. military aid.

The United States relied on Sunni tribesmen to assist its fight in al-Qaeda through the Awakening Movement, or Sahwa. Maliki attempted to revive the movement earlier this year as ISIS took over the two main cities in Anbar province, but the effort has been hampered by deep dissatisfaction among Iraq’s Sunni community with Maliki’s government.

Jabbouri said his men, tens of whom have been reported killed in the clashes, were not being paid but were fighting to “avenge” the ISIS attack on the country. He said his tribesmen were largely fighting on the perimeters of the facility, while government forces were inside and in control of the refinery on Thursday. He declined to say how many of his men were fighting.

As violence grips Iraq, the death toll is spiraling. Some 2,764 civilians have died from violence in Iraq so far in June, according to Iraq Body Count, which monitors the death toll. That figure is already more than double the 1,027 killed in May and the highest monthly death toll since May 2007, according to the group.

In Washington, Gen. Martin E. Dempsey, chairman of the Joint Chiefs of Staff, said Wednesday that the Iraqi government has formally asked Washington to provide “air power” as it tries to take back territory seized by insurgents. Iraqi officials have said their army, which offered little resistance as it retreated from several northern cities last week, needs help in the form of armed U.S. drones and fighter aircraft.

ISIS insurgents fired mortars at the oil refinery in Baiji, forcing the temporary shutdown of Iraq's largest gasoline processing plant. Here's what you need to know about the strategic importance of this refinery. (Davin Coburn and Kate M. Tobey/The Washington Post)

But President Obama so far has declined to authorize such strikes, and administration officials have told Congress that a bombing campaign would be complicated and that Iraq’s political divisions need to be addressed first.

The lack of airstrikes from the United States is playing into the hands of ISIS, said Mussawi, the government spokesman.

“The slow response to this request gives support to the terrorists and makes them stronger,” he said. “This is not only endangering Iraq, but the whole world.”

Obama briefed congressional leaders Wednesday on options for quelling the insurgency by ISIS, which launched a lightning offensive across northern Iraq last week.

U.S. airstrikes, while not yet fully ruled out, are not imminent, U.S. officials said, partly because intelligence agencies have not been able to pinpoint clear targets on the ground.

The Obama administration is pushing Maliki’s Shiite-led government, which faces widespread disaffection among its people, for an inclusive political solution. U.S. officials say the Iraqi leader has not done enough to accommodate Iraq’s Sunni minority, contributing to the present crisis.

The oil refinery at Baiji, 140 miles northwest of Baghdad, provides the nation with more than a quarter of its domestically refined petroleum products and could help fund the

militants’ strike across the country.

A gas shortage has crippled transportation in Kurdish-controlled areas of Iraq’s north, 10 days after the Sunni jihadists swept into the key city of Mosul and seized territory across a broad swath of the country.

The largely autonomous and relatively safe Kurdistan region is now bearing the brunt of the militants’ offensive, as hundreds of thousands of displaced Iraqis flood north from the danger zone, crossing into Kurdish-controlled areas and creating a strain on resources.

Northern Iraq depends on the Baiji refinery to refine oil from the now Kurdish-controlled oil-producing area of Kirkuk.

Across Kurdish provinces this week, residents and refugees queued in hours-long lines for gas, some people spending a full night in their cars waiting for a gas station to open. Many stations appeared to have shut down completely.

At one gas station in the Kurdish regional capital of Irbil, a riot broke out early Thursday. People who had been waiting in line for hours grew furious when gas station workers suddenly shut the station down. Kurdish police fired shots in the air to control the crowd, one witness said.

In a televised address Wednesday, Maliki struck an upbeat tone on the security situation even as fighting raged at Baiji. He said volunteers who answered a call to arms from Iraq’s top Shiite cleric will form the core of new Iraqi security forces. The government hopes the recruits will help plug gaps in the army after mass desertions but is desperate for outside assistance.

Perhaps in an attempt to satisfy the United States, Maliki’s speech lacked some of the religious rhetoric of previous addresses. But he accused his political opponents of assisting countries in the region in a “sinister” plot to break up Iraq.

The Baiji oil facility has been shut down for several days. State Department spokeswoman Jen Psaki confirmed that production at the plant had stopped because of a “combination of technical and security reasons.”

The shutdown of the domestic oil facility will have little impact on exports of crude oil, she said.

Hauslohner reported from Irbil. Daniela Deane contributed to this report from London.