The United Nations chief weapons inspector has criticised the quality of the intelligence given to him by the United States and Britain about Iraq's alleged weapons of mass destruction.
Hans Blix is due to retire at the end of the month
Hans Blix told the BBC that his teams followed up US and British leads at suspected sites across Iraq, but found nothing when they got there.
A team of UN nuclear inspectors will arrive in Iraq on Friday, but the United States will only allow it to carry out a limited inspection at a nuclear storage facility.
The BBC's Greg Barrow at the UN says Mr Blix's comments will add to the growing controversy over the quality of intelligence used in the run-up to the Iraq war.
However US Defence Secretary Donald Rumsfeld has insisted that the information had been good.
I thought - my God, if this is the best intelligence they have and we find nothing, what about the rest?
In a BBC interview on Thursday, Mr Blix said he had been disappointed with the tip-offs provided by British and US intelligence.
"Only in three of those cases did we find anything at all, and in none of these cases were there any weapons of mass destruction, and that shook me a bit, I must say."
He said UN inspectors had been promised the best information available.
"I thought - my God, if this is the best intelligence they have and we find nothing, what about the rest?"
On Thursday, the chief weapons inspectors gave what is likely to be his last report to the UN Security Council before he retires later this month.
His briefing recorded an open verdict over whether Iraq had weapons of mass destruction.
WERE WE MISLED OVER WMD?
I supported the war, with or without the discovery of WMD, but if there are questions of deception then there must be an inquiry - democracies must remain open
Shawn Hampton, Oregon, US
Saddam Hussein's regime might have hidden weapons, or it might have destroyed them, Mr Blix said.
But following the fall of Saddam Hussein, he said, the conditions were now right for the truth to come out either way.
In his report, which covers the last three months since inspectors were withdrawn before the US-led invasion of Iraq, Mr Blix said Iraq had left "many unanswered questions" about its non-conventional weapons, but this did not mean such dangerous arms still existed.
Both US and British intelligence sources have told the BBC that evidence against Iraq was distorted in order to justify the war against Iraq.
However the US administration has defended the intelligence it presented.
US President George W Bush on Thursday said it would take time to find Iraq's chemical and biological weapons, but he promised to "reveal the truth" about them.
"Saddam Hussein's got a big country in which to hide them. Well, we'll look," President Bush told US troops in Qatar.
Mr Rumsfeld, for his part, said the case put before the UN Security Council by US Secretary of State Colin Powell in February would in time "be proved accurate".
However the defence secretary added that his department would co-operate with any Congressional investigation into the issue.
The inspectors looked, but found little incriminating evidence in Iraq
The US has rejected calls for the return of UN inspectors to hunt for Iraqi weapons.
But it has said it plans to widen the search, by interviewing low-ranking officials and relying on interrogations of alleged war criminals.
A small team from the International Atomic Energy Agency (IAEA) is due to arrive in Iraq on Friday to check on looting of atomic materials, but the US has barred it from visiting all but one site at the Tuwaitha nuclear research complex south of Baghdad.
US Defence Department officials quoted by Reuters news agency are insisting that US troops accompany the UN inspectors at the site, and that the visit sets no precedent for a future role in Iraq for the IAEA.