Two suicide bombers have attacked offices of the two main Kurdish parties in northern Iraq, killing at least 56 people, including top officials.
Announcing the death toll, US General Mark Kimmitt also said more than 200 people were injured by the blasts on Sunday morning in Irbil.
In virtually simultaneous attacks, the bombers hit offices packed with guests for the Muslim holiday of Eid al-Adha.
Kurdish officials blamed al-Qaeda and its allies for the attacks.
They said they feared the death toll could rise above 100.
Irbil hosts the Kurdish parliament, which brings together the two factions - the Kurdistan Democratic Party (KDP) and the Patriotic Union of Kurdistan (PUK).
The KDP and PUK between them largely run northern Iraq and are strong allies of the US-led coalition which ousted Saddam Hussein.
Iraqi Foreign Minister Hoshiyar Zebari - a Kurd - blamed the Muslim militant group Ansar al-Islam for the attack.
The Kurds and the United States say the group is allied with Osama Bin Laden's al-Qaeda network.
'Senior officials killed'
Ansar al-Islam was expelled from northern Iraq by Kurdish and coalition forces during last year's war.
But PUK spokesman Sabah Sabir told the BBC that Ansar had recently re-emerged because of the increasing volatility in Iraq.
Security was said to be lax because of the holiday, a major event for Muslims.
Mohammed Ihsan, minister for human rights for the Kurdish regional government, told the Associated Press that he thought about 140 had died in the attacks.
He said among the dead were senior figures in the provincial government - including Governor Akram Mintik, Deputy Prime Minister Sami Abdul Rahman, Minister of Council of Ministers Affairs Shawkat Sheik Yazdin and Agriculture Minister Saad Abdullah.
The director of Irbil's city morgue, Tawana Kareem, told AP that 57 bodies had been brought in, some of which had then been taken away by relatives.
"Figures are increasing," Mr Kareem added.
The BBC's Barbara Plett reports that the morgue was so full that bodies were lying under covers in the bloodstained corridors.
The bombers, witnesses said, made their way through checkpoints outside both venues and detonated their bomb belts once inside.
"On the first day of Eid we receive people and well-wishers and that's why security wasn't as tight as during the rest of the days," said Mohammed Ihsan.
"They [the attackers] took advantage of this."
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