Two suicide bombers have attacked offices of the main Kurdish parties in north Iraq, killing at least 56 people.
Hundreds of guests were in the offices for the Eid festival
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 Irbil attacks and said they feared the death toll could rise above 100.
The KDP and PUK between them largely run northern Iraq and are strong allies of the US-led coalition which ousted Saddam Hussein.
Irbil hosts the Kurdish parliament, which brings together the two main factions - the Kurdistan Democratic Party (KDP) and the Patriotic Union of Kurdistan (PUK).
The US chief administrator in Iraq, Paul Bremer, denounced the bombings as "a cowardly attack on innocent people".
'Senior officials killed'
Iraqi Foreign Minister Hoshiyar Zebari - a Kurd - blamed the Muslim militant group Ansar al-Islam for the attacks.
The Kurds and the United States say the group is allied with Osama Bin Laden's al-Qaeda network.
Ansar al-Islam was expelled from northern Iraq by Kurdish and coalition forces during last year's war.
MAJOR ATTACKS SINCE 1 MAY
1 February 2004: At least 56 killed by twin suicide bombings during celebrations in Kurdish city of Irbil
18 January 2004: 18 reported killed outside coalition HQ, Baghdad
14 December: Car bomb at police station kills 17 in Khalidiya, west of Baghdad
12 November: 26 die in suicide attack on Italian base in Nasiriya
2 November: 16 US soldiers die as Chinook helicopter downed
27 Oct: Red Cross and other buildings in Baghdad bombed, more than 30 killed
29 Aug: Mosque near Najaf bombed, at least 80 dead including top Shia cleric
19 Aug: UN headquarters in Baghdad bombed, 23 killed including head of mission
List covers attacks since US declared war effectively over
But PUK spokesman Sabah Sabir told the BBC that Ansar had recently re-emerged because of the increasing volatility in Iraq.
Mohammed Ihsan, minister for human rights for the Kurdish regional government, said the dead included senior figures in the provincial government - Irbil Governor Akram Mintik, Deputy Prime Minister Sami Abdul Rahman, Minister of Council of Ministers Affairs Shawkat Sheik Yazdin and Agriculture Minister Saad Abdullah.
The BBC's Barbara Plett reports that the morgue in Irbil 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."
In other developments:
- US officials say President Bush will soon announce details of an independent investigation into the use of intelligence material to justify the Iraq war.
- One US soldier was killed and 12 wounded on Sunday in a rocket attack on a US logistics base in Balad, 80 kilometres (50 miles) north of Baghdad, the US military reported. Sixteen Iraqis were arrested after the attack.
- An explosion at a munitions depot early on Sunday about 180 kilometres (112 miles) south-west of Karbala in central Iraq killed an unknown number of Iraqi looters , coalition forces said.