At least 45 people have been killed and dozens wounded by a suicide truck bombing in the northern Iraqi town of Makhmur, police said.
The blast in Baghdad was near a popular commercial area
The bomber crashed his truck into the offices of a leading Kurdish party, the Kurdistan Democratic Party, where a meeting was being held at the time.
It was the second suicide attack in the mainly Kurdish area in the past week.
In Baghdad, at least 10 people died when a car bomb exploded near a market in the mainly Shia Sadriya district.
Some 45 people were wounded when the bomb exploded on Wathba Square near the popular commercial area.
The blast left a small crater in the ground filled with debris from the car and surrounding buildings.
A car bombing in the same area last month killed 140 people, the bloodiest attack since a recent US security operation began in the capital.
Sunday's attack on the town of Makhmur in Irbil Province targeted the local office of the Kurdistan Democratic Party (KDP), which was holding a meeting at the time.
The KDP is led by the president of the Kurdish autonomous region, Massoud Barzani.
Local government buildings were also damaged by what witness said was a very large explosion, and a senior police officer was among the dead.
The town's mayor, prominent Kurdish writer Abd al-Rahman Belaf, was one of the many wounded taken for medical treatment to the nearby provincial capital of Irbil, about 50km north-east of Makhmur.
Makhmur's police chief said many bodies were buried under rubble and that he expected the death toll to rise.
Last week, 14 people were killed by a truck bomb in Irbil.
Political tensions have been rising in the predominantly Kurdish region over the drafting of a bill that will redistribute oil wealth among the country's Kurdish, Sunni and Shia population.
Most of Iraq's oil is concentrated around the Kurdish north and Shia south.
Search for troops
Meanwhile, US forces have stepped up efforts to find three US soldiers who are missing after their patrol was attacked south of Baghdad on Saturday.
A spokesman, Maj Gen William Caldwell, confirmed on Sunday that an Iraqi interpreter was among the five members of the patrol who were killed in the attack in Mahmudiya. The other dead members were Americans.
On Sunday, a group associated with al-Qaeda in Iraq, calling itself Islamic State in Iraq, posted a statement on the internet claiming responsibility for the attack and saying that it was holding the missing soldiers.
The group offered no proof to back up its claim.
Gen Caldwell said more than 4,000 US troops, as well as Iraqi units and aerial surveillance aircraft, were now involved in the search.
The US commander also announced that an additional 3,000 soldiers were being deployed in Diyala Province to deal with rising violence.
Last week, the US commander in the north, Maj-Gen Benjamin Mixon, said the Iraqi government's support for its own forces and provincial authorities was at times ineffective.
"There is recognition clearly that up in Diyala there has been an uptick in the violence," Gen Caldwell said.