UN shocked by its most devastating attack

The United Nations secretary general, Kofi Annan, broke off his holiday and headed for New York last night to confer with senior officials after the most devastating attack in the history of the organisation.

Flags at the UN building were at half-mast in honour of its special representative, Sergio Vieira de Mello, 55, a Brazilian, who was among 20 people killed in the suicide vehicle bomb attack at the UN's Canal Hotel offices in Baghdad. At least 100 people were injured, some seriously.

Mr Annan said: "Nothing can excuse this act of unprovoked and murderous violence against men and women who went to Iraq for one purpose only: to help the Iraqi people recover their independence and sovereignty, and to rebuild their country as fast as possible, under leaders of their choosing."

But a row has started over who was responsible for security at the building. The UN said allied forces were responsible and that its own staff was not trained or equipped to prevent such attacks. The Pentagon in turn claimed the UN and the recently established Iraqi police force were primarily responsible for security. Ahmad Fawzi, who until last month was spokesman for Mr Vieira de Mello, told The Independent: "Under [the] Geneva Convention, the coalition is responsible for the security in the country. We had American soldiers protecting the compound on the outside. Our men are unarmed. We have limited security."

The Pentagon said a small number of US soldiers had been on security detail on the far side of the UN building, used by international officials, journalists and aid workers as well as Iraqi staff.

President George Bush described those responsible for the bombing as "enemies of the civilised world". He said: "These killers will not determine the future of Iraq. Every sign of progress in Iraq adds to the desperation of the terrorists and the remnants of Saddam's brutal regime."

'All of us are shocked and dismayed ... Nothing can excuse this act of unprovoked and murderous violence'

KOFI ANNAN

'By their tactics and targets, these murderers reveal themselves once more as enemies of the civilised world'

GEORGE BUSH

'These are plainly very, very reckless people, of a type who sustained the Saddam regime'

JACK STRAW