BAGHDAD—Gunmen in military uniforms stormed Iraq’s central bank on Sunday in an apparent robbery attempt, battling security forces in a three-hour standoff after bombs exploded nearby in an attack that left at least 15 people dead.

The assault on Iraq’s top financial institution stoked fears that insurgents are taking advantage of the political deadlock after inconclusive March 7 national elections to try to derail security gains. The 325-member parliament was to convene Monday, but agreement on a new government could still be months away, analysts say.

Iraqi military spokesman Maj. Gen. Qassim al-Moussawi blamed the attack on al Qaeda in Iraq, but said no money had been stolen from the bank, which holds gold deposits as well as U.S. and Iraqi currency.

The violence began with the brazen daylight bombings, which sent plumes of smoke over the city skyline. There were conflicting reports about the number and nature of the blasts. Some Iraqi police and hospital officials put the toll as high as 26 dead and more than 60 wounded.

The first bomb went off on the road near an electrical generator, Gen. al-Moussawi said. Insurgents wearing army uniforms then tried to enter the bank through two entrances, exchanging gunfire with the guards. Three suicide bombers detonated explosive vests at the main entrance of the bank, the general said, while two other militants were killed by security forces at the second gate. Iraqi security forces then stormed the building, prompting a standoff that lasted at least three hours, the general said.

An unknown number of attackers managed to get to a higher floor and set a fire to burn some documents, the general said. They may have escaped by blending in with bank employees, he said; the motive appeared to be to steal the bank’s deposits, then blow up the building.

Local police said a bomb in a parked car also exploded about 900 yards from the bank.

Ghayth Abdullah, the 37-year-old owner of a nearby clothing store, said the blast sent people running from the site, including dozens of women who worked at the bank. He blamed the government for failing to protect people. “I was not thinking about my property or livelihood,” Mr. Abdullah he said. “My worry was what would happen to my family if I were killed by the blast or random shots from the crossfire.”

Violent robberies that bear some of the hallmarks of politically motivated attacks have been on the rise in Iraq, as sectarian violence ebbs. Iraqi officials have attributed some of them to cash-strapped militants desperately trying to raise money for their operations.

Sunday’s attack appeared also to have a political motive as insurgents led by al Qaeda in Iraq seek to undermine confidence in the U.S.-backed government and other state institutions. It was reminiscent of violence that was common at the height of sectarian tensions that pushed the country to the brink of civil war in 2006-2007 before a series of U.S.-Iraqi offensives.

Insurgents have targeted government institutions several times over the past year.

The narrow victory of the Sunni-backed Iraqiya party in the March 7 parliamentary vote was initially heralded as a groundbreaking step toward a secular Iraqi government after years of Sunni-Shiite tensions. But an alliance between Prime Minister Nouri al-Maliki and another major Shiite coalition, brokered with the help of Iran, has sparked months of political maneuvering, leaving the government in limbo.

In a sign resolution was still far away, senior Iraqiya member Hassan al-Allawi said he wouldn’t lead Monday’s opening parliamentary session as planned, saying it would take up to five months to form a government and he didn’t want to hold the job that long. He said he has handed over the job to Kurdish lawmaker Fouad Massoum.

Earlier Sunday, an independent public watchdog said Iraq’s government suffered more corruption last year than any other since the U.S.-led invasion in 2003. Rahim al-Ogaili, chairman of Iraq’s Commission on Public Integrity, cited 7,797 cases of waste, fraud and abuse in 2009 that resulted in the loss of about 842 billion Iraqi dinars, or about $718 million. He didn’t give details about how the money was wasted, or the total funds lost since 2003.

Mr. al-Ogaili, whose panel reports to parliament, said Iraqi leaders largely ignore evidence of corruption, adding: “There are no real and serious measures to fight it.”

—Copyright 2010 Associated Press