Bomb attacks in the northern Iraqi oil city of Kirkuk have killed at least 85 people and wounded more than 180.
Kirkuk has seen a recent rise in the number of attacks
A suicide bomber detonated a lorry near the offices of a Kurdish political party, the Patriotic Union of Kurdistan (PUK), causing most of the casualties.
Two other bombs later went off in the city. No group has claimed the attacks.
The status of Kirkuk is disputed by Arab Iraqis, Kurds and Turkmen. The number of bombings in the region has been increasing in recent months.
Witnesses to the attack on the offices of the PUK - a party led by Iraqi President Jalal Talabani - said the massive explosion there left a crater several metres deep.
More than 20 cars were destroyed, two buildings collapsed completely and a number of shops were also damaged.
Dozens of bodies are said to be buried in the rubble and the death toll is expected to rise.
MAJOR ATTACKS IN 2007
16 July: At least 85 die in twin bombings in Kirkuk
7 July: 130 killed in Amirli market bombing
19 June: At least 78 die in Baghdad mosque blast
18 April: Up to 200 killed in car bombings in Baghdad
29 March: At least 60 killed in double suicide bombing in Baghdad market
6 March: At least 90 killed in double suicide bombing in Hilla
3 Feb: At least 130 die in suicide truck bombing in Baghdad
22 Jan: 88 killed in Baghdad car bombings
"Most of the wounded, which include women and children, are in a critical condition," Kirkuk's police chief told AFP news agency.
In the second attack, about 15 minutes later, a bomber struck a bus station at a nearby market, which was largely empty after the first bombing. One civilian was wounded.
Several hours later, a car bomb exploded in southern Kirkuk, killing a police officer and wounding six other policemen, officials say.
The BBC's Mike Sergeant in Baghdad says Kirkuk police managed to arrest the bus station bomber.
Tensions have risen in Kirkuk area, where the Iraqi government is planning to hold a referendum by the end of the year.
The city lies outside Iraqi Kurdistan but is claimed by many Kurds for their national capital.
On 7 July a truck bomb killed 105 people at a market in the town of Amirli, south of Kirkuk.
Meanwhile, in the capital Baghdad a series of attacks on Monday morning killed at least nine people.
In the deadliest of the attacks, a roadside bomb hit an Iraqi army patrol on the city's north-eastern outskirts, killing five soldiers and wounding nine others.