Annan's speech to UN staff

In an emotional video address from New York to thousands of UN staff around the world, Mr Annan said the UN would "continue helping Iraqis", but he acknowledged that the way it operates may have to be changed.

Expressing grief and sadness over the deaths of UN personnel in Baghdad, Mr Annan said they had been the victims of the most deliberate and vicious attack in the organisation's history.

"Thank you for your tremendous fortitude... Your work has been a source of inspiration to all of us and... the people of Iraq," Mr Annan said.

We have 20 colleagues deceased, some of them not yet identified. We have 86 colleagues seriously injured Ramiro Lopez da Silva, UN official in Iraq

"Each of these men and woman made a unique and invaluable contribution to our work...and well-being of the Iraqi people," he said before announcing a minute of silence to honour the memory of the victims.

Mr Annan was speaking after meeting US Secretary of State Colin Powell, who said Washington was drafting a new UN resolution to encourage more member states to send troops to Iraq.

UN staff still missing

Earlier, UN Humanitarian Co-ordinator for Iraq Ramiro Lopez da Silva said that the organisation would move to a new facility within three to four days and would resume its activities on Saturday.

The blast tore off a corner of the UN building

But Mr da Silva - with his face still bandaged from the attack - told a news conference in Baghdad that the number of UN staff in the Iraqi capital was being reduced.

"We were about 300 in Baghdad on Tuesday. We will be about 200 in Baghdad as of Saturday at work," Mr da Silva said.

Referring to the latest figures on the death toll after the blast, Mr da Silva said that "at this moment we have 20 colleagues deceased, some of them not yet identified".

"We have 86 colleagues seriously injured in several facilities in Baghdad and around Baghdad," he said, adding that two UN staff members were still missing.