BAGHDAD, June 25 (Xinhuanet) -- More than 100 people, mostly Iraqi civilians, were killed in a series of attacks mounted by Iraqi militants on Thursday in the Sunni-dominated central Iraq and oncerelatively quiet northern Iraq.

    The sharply increased violence was viewed widely as an attempt to sabotage the June 30 handover of power from the US-led occupation to the Iraqi interim government.

    An extremist Islamic group led by suspected al-Qaida ally Abu Mussab Zarqawi claimed responsibility for Thursday's attacks.

    A large number of people were killed in five car bombings in the northern city of Mosul, but some also died during the airstrikes by US warplanes. And at least 320 people were wounded, including 12 Americans.

    The offensive in at least six cities, namely Baghdad, Baquba, Ramadi, Fallujah, Mosul and Mahaweel, showed an unusual level of coordination. The attacks appeared to surprise even US officials who had been aware that militants would create chaos before the transfer of power.

    "We underestimate the nature of the insurgency that we might face during this period, and so the insurgency that we are lookingat now ... has become a serious problem for us," US Secretary of State Colin Powell told the British Broadcasting Corporation.

    However, Iraqi Prime Minister Iyad Allawi said the attacks werenot coordinated, adding that the remnants of former Baathists loyal to former president Saddam Hussein were probably behind the violence in Ramadi and Baquba.

    The assaults were launched at dawn when guerrillas attacked police stations and government buildings in central and northern Iraq. US troops responded by calling in warplanes and helicopters and dropping 11 225-kg bombs and one 900-kg bomb.

    The heaviest fighting was in Baquba, 60 km northeast of Baghdad,where 19 Iraqi policemen and two US soldiers were killed in multiple assaults targeting government offices and police posts.

    Militants brandished automatic weapons and rocket-propelled grenades in empty streets after coalition forces withdrew from Baquba, according to the Qatar-based Arabic-language satellite television network al-Jazeera.

    Pamphlets were distributed in the town, claiming that Abu Mussab Zarqawi waged the attacks to revenge US airstrikes in the flash-point city of Fallujah, which also witnessed fierce clashes on Thursday.

    Sporadic fighting between US Marines and insurgents in Fallujahcontinued till Friday morning and two people were killed and sevenwounded.

    In the Kurdish-controlled northern city of Mosul, touted as a success story in restoring order in Iraq, five car bombs exploded on Thursday, killing 62 people, including a US solider, and wounding more than 220 others.

    In Ramadi, 108 km west of Baghdad, armed groups attacked policestations with rifles, AK-47 machine guns and rocket-propelled grenades. At least 20 people were killed in the city, according tothe Health Ministry. Enditem