Iraqi officials say a wave of bombings has killed at least 39 people and wounded 74 others.

Authorities said the attacks Monday included a car bomb exploding in the capital, Baghdad, as well as a series of explosions in the northern city of Kirkuk. Other deadly attacks targeted Taji, just north of Baghdad.

There was no immediate claim of responsibility.

The violence comes after jihadist websites posted a message Saturday, purportedly from the leader of al-Qaida's affiliate in Iraq, saying the group is starting a “new phase.” The audio message from a speaker identified as Abu Bakr al-Baghdadi says the Islamic State of Iraq is planning to attack court officials, and to free prisoners.