A series of explosions have rocked the northern Iraqi city of Kirkuk, killing at least 18 people, while several people were injured in Erbil, capital of the Kurdish region, officials said.
Two of three near-simultaneous car bombs in Kirkuk on Saturday exploded near buildings under construction that were used as observation positions by security forces, while the third struck the entrance to a market.
The blasts come as Iraqi and Kurdish troops are fighting back an offensive by the Islamic State group in the north and as sectarian attacks have deepened the country's crisis.
More than 100 people were injured in the Kirku blasts.
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A police colonel said that the market blast may have been a suicide car bombing, while a doctor said that three security forces members were among the dead.
In Erbil, the capital of the autonomous Kurdish region, local television network Rudaw showed firefighters dousing the charred remains of a car outside a technical college on a road from Erbil to Kirkuk.
Seven people were reported wounded but none killed in the blast.
While much of Iraq has been plagued by near-daily violence, Kurdistan's capital has avoided much of the deadly unrest.
Al Jazeera's Zeina Khodr, reporting from Erbil, said the explosion went off on a road near the office of the Patriotic Union of Kurdistan (PUK), a group which has recently engaged in fighting against the Islamic State group.
The last major attack in Erbil was in September, when fighters launched a coordinated suicide and car bomb attack on the headquarters of the security services.
Earlier on Saturday, in the capital Baghdad, a suicide bomber drove an explosives-laden car into the intelligence headquarters, killing six civilians and five security personnel, apparently in retaliation for an assault on a Sunni mosque.
Parliament speaker Salim al-Jabouri said a committee was probing Friday's attack against a village mosque in Diyala province, which killed at least 73 people.
It remained unclear whether the attack in the village of Imam Wais was carried out by Shia militiamen or fighters from the Islamic State group.
Iraqi federal and Kurdish security forces are battling the Islamic State group's 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.
Iraqi Kurdistan enjoys a high level of autonomy from Baghdad, and the regional parliament has passed laws on a wide range of issues.
Source: Al Jazeera and agencies