The attacks in Kirkuk began around noon when a suicide bomber detonated his explosives-packed truck near the concrete blast walls of the headquarters of the Patriotic Union of Kurdistan, the party of Iraqi President Jalal Talabani.

The explosion blasts a 30-foot-deep crater in the pavement and collapsed part of the roof of the one-story PUK office. Outside the offices, the burnt shells of more than two dozen vehicles were in the street.

Soon after, the second bomber attacked the Haseer market, 700 yards away, destroying stalls and cars, said Kirkuk police Brig. Sarhat Qadir.

The Haseer market an outdoor souk with stalls of vegetable and fruit sellers is frequented by Kurds in Kirkuk, a city where tensions are high between the Kurdish and Arab populations. At least 80 people were killed and around 140 wounded, said police Brig. Burhan Tayeb Taha.

The attack was believed to be the deadliest suicide bombing in Kirkuk 180 miles north of Baghdad where violence tends to be on a smaller scale of shootings, roadside bombs and kidnap-slayings, often linked to the struggle between the city's Kurds and Arabs. Monday's blast came just over a week after one of the Iraq conflict's deadliest suicide attacks hit a village about 50 miles south of Kirkuk, killing more than 160 people.

Iraqi officials have said Sunni insurgents are moving further north to carry out attacks, fleeing US offensives in and around Baghdad, including in the city of Baqouba, a stronghold of extremists on the capital's northwestern doorstep. The month-old sweeps, fuelled by the "surge" of 28,000 new American troops sent to Iraq this year, aim to pacify the capital and boost the government of Iraqi Prime Minister Nouri al-Maliki.

US troops launched a new offensive south of Baghdad on Monday, aimed at stopping weapons and fighters from moving into the capital, the military said in a statement.

The statement did not say where the new sweep, codenamed Marne Avalanche, was taking place. Cut in recent days US commanders have said they plan new operations to cut off an insurgent supply route southwest of the city, running from western Anbar province. An offensive has been ongoing for the past month in a region southeast of Baghdad.

Violence appears to have eased in Baghdad in recent weeks but attacks, including deadly car bombs, happen daily.

A string of attacks Monday morning in the capital killed at least 14 people.

In the deadliest, a roadside bomb exploded as an Iraqi army patrol passed in the city's northeast outskirts, killing five soldiers and wounding nine, an army officer said.

Two car bombs struck, one driven by a suicide bomber who struck a police checkpoint on a major road leading to a major Interior Ministry building inside the Green Zone. Two policemen were killed and seven people wounded, a police official said.

A parked car bomb went off in the central district of Karradah on Monday, exploding near Masbah Square, killing one person, wounding three others and leaving nearby shops burned, a police official said. On Sunday, a car bomb went off about a half-mile away, killing 10 people.