BAGHDAD - The Iraqi government expressed frustration Thursday over U.S. reluctance to launch air strikes 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 air strikes 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. About 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 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.

But President Obama so far has declined to authorize such strikes. 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 air strikes 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. air strikes, 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.