BAGHDAD – The bloodiest day of the year in Iraq left at least 69 people dead in a series of bombings in mainly Shiite areas Friday. The concerted attacks were seen as demonstrating the resilience of the Sunni-led insurgency after the slaying of two al-Qaida leaders last weekend.

No one has taken responsibility for the blasts, but officials were quick to blame Sunni-led insurgent groups for attacking at a particularly fragile time as Iraq awaits formation of a new government and prepares for U.S. troops to go home by the end of next year.

The protracted political wrangling since contentious March 7 elections has raised fears of sectarian violence akin to that seen at the height of the war.

Prime Minister Nouri al-Maliki lashed out at the bombers in a statement Friday night, saying the insurgents were trying to fight back after Iraqi security forces killed the two al-Qaida in Iraq leaders on April 18.

“The cowardly terrorist attacks that occurred today were intending to cover the great success achieved by the security forces through the killing of the leaders of wickedness and terrorism, Abu Omar al-Baghdadi and Abu Ayyub al-Masri,” al-Maliki said.

Friday’s apparently coordinated attacks came in a two-hour span shortly after the Shiites’ call to prayer across the capital. The major blasts were in former Shiite militia strongholds, underscoring the insurgents’ professed aim of provoking a new round of sectarian bloodshed. Among the targets of the car and roadside bombs were three Shiite mosques.

In the vast eastern Baghdad slum of Sadr City, four strategically located car bombs timed to maximize the carnage killed at least 36 people and wounded nearly 200, according to hospital and police officials who spoke on condition of anonymity because they were not authorized to talk to the media.

Flames shot out of nearby parked cars and motorcycles. Blood mixed with water streamed down muddy streets as firefighters worked to put out the blazes, and passers-by frantically tried to help. Shouting men loaded the wounded onto trucks to rush them to the hospital.

Sadrist lawmaker Bahaa al-Aaraji said Iraq’s leaders were more intent on jockeying for position than protecting people.

“Prolonging the time to form the government will pave the way for more attacks,” he said. “These attacks represent a warning to the political blocs that they should speed up their efforts to form the government.”