BAGHDAD — Al-Qaida's branch in Iraq says it carried out a wave of bombings that killed at least 82 people, mostly in Shiite areas in the capital, in retaliation for the execution of Sunni prisoners by the Shiite-led government.

In a statement posted Friday, the Islamic State of Iraq and the Levant, the al-Qaida affiliate in Iraq, took responsibility for the deadly attacks earlier this week, mainly car bombs targeting marketplaces and parking lots.

The authenticity of the statement could not be independently confirmed. It was posted on a website commonly used by jihadists and its style was consistent with earlier al-Qaida statements.

More than 4,000 people have been killed in violent attacks in Iraq since the start of April, when the pace of killing accelerated to levels unseen since 2008.