Smoke rises from a oil refinery in Baiji, north of Baghdad June 19, 2014.
A suicide bomber in a truck packed with explosives killed a senior police commander involved in an operation against Islamic State militants who have been surrounding Iraq's biggest oil refinery for months, security sources said.
Friday's attack killed General Faisal Malik, one of the supervisors of a campaign designed to break the Sunni insurgents' grip on the facility and to rescue security forces trapped inside it just outside the town of Baiji.
Two policemen were also killed, the security sources said.
"The general was in his Humvee with two of his men. A suicide bomber in a truck targeted him directly," said an officer under his command.
Iraqi security forces have repeatedly tried to push Islamic State fighters out of the refinery compound, where security forces have been surviving on airdrops.
The death of Malik came after Iraqi security tried a new strategy to break the Islamic State siege of the refinery near Baiji, which lies 200 km (130 miles) north of Baghdad.
Backed by Shi'ite militias and army helicopters, government forces have swept through a desert area west of Baiji, hoping to recapture the town and to cut off Islamic State supply lines.
Security forces were also hoping to gain control of a road leading to Mosul, the biggest city in the north which is held by Islamic State, according to an army colonel.
Islamic State fighters seized the city of Baiji and surrounded the sprawling refinery in June during a lightning campaign through northern Iraq. The group also controls a swathe of territory in neighbouring Syria and has proclaimed a caliphate straddling both countries.
The police general's death was a psychological blow for the government after it had capitalised on U.S. air strikes against Islamic State and regained some territory.
CORRUPTIONThe prime minister's office said on Friday that security forces had hoisted the Iraqi flag on a bridge that connects to the town of Amriyat al-Falluja, 40 km (25 miles) from Baghdad.
It was not immediately possible to get independent confirmation that government forces had advanced.
Islamic State fighters have been surrounding the area, located near the militants' stronghold of Falluja, for weeks.
Western officials say Islamic State can only be defeated if the Iraqi army dramatically improves its performance.
Reflecting such concerns, U.S. officials told Reuters on Friday the U.S. military had drawn up plans to significantly increase the number of American forces in Iraq beyond the current total of around 1,400 as part of a drive to help the Iraqi army defeat Islamic State.
Iraq's most influential Shi'ite cleric blamed corruption in the armed forces for Islamic State's advances, criticism that will add to pressure for reforms in the face of the insurgency.
Grand Ayatollah Ali al-Sistani has been sharply critical of Iraqi leaders during what has become Iraq's worst crisis since a U.S.-led invasion toppled Saddam Hussein in 2003, urging them to set aside sectarian differences to save the nation.
Iraq's army, recipient of $25 billion in U.S. training and funding, collapsed in the face of the rebels' summer onslaught.
Speaking on Friday on live television through an aide in the holy southern Iraqi city of Kerbala, Sistani, 84, asked rhetorically what would happen if the military were corrupt.
"We think the security deterioration that happened some months ago can answer that," Sistani said.
"Objectivity demands that the different military positions should be occupied by those who are professional, patriotic, faithful, courageous and not affected in doing their duties by personal and financial influences."
Sistani, whose word is law for millions of followers, went on to say that "even the smallest corruption is big". The reclusive cleric always delivers public messages via a proxy.
U.S. air strikes have prevented Islamic State making further large-scale advances since August, when the al Qaeda offshoot beat back Kurdish peshmerga forces in the north and triggered a massive exodus of minority communities.
Lacking a strong army, Iraq's government turned to Iranian-backed Shi'ite militias. But their alleged violations of human rights have exacerbated sectarian tensions, with the Sunni minority complaining of kidnappings, torture and executions.
Militia leaders deny those accusations.
Even if more Western countries step up support for Iraq's military, the overriding question will be whether the Shi'ite-led government can revive an alliance with Sunni tribesmen who helped defeat al Qaeda during the U.S. occupation.
© Thomson Reuters 2014