Three near-simultaneous car bombs exploded in the northern Iraqi city of Kirkuk on Saturday, killing 21 people and wounding 118, a senior police officer and a doctor said.
Two of the bombs exploded near buildings under construction that were used as observation positions by security forces, while the third struck the entrance to a market.
The bombings come as Iraqi federal and Kurdish security forces battle a jihadist-led militant offensive that was launched in June and has overrun large areas of five provinces.
In the early days of the onslaught, Iraqi soldiers left their positions in oil-rich Kirkuk province, the capital of which is the city of the same name.
This cleared the way for Kurdish forces to take control of it and other disputed northern areas that they have long wanted to incorporate into their autonomous region, over the strong objection of Baghdad.