President George Bush has dismissed doubts about the existence of Saddam Hussein's alleged chemical and biological arsenal.
Controversy over Iraq's alleged WMD rages on
In a speech to US troops in the Gulf Emirate of Qatar, Mr Bush promised to "reveal the truth" about Iraq's weapons of mass destruction (WMD).
His comments come as controversy continues to mount about how imminent a threat the Saddam Hussein regime posed before it was ousted by US-led forces.
A well-informed source close to British intelligence has told the BBC that drafts of last September's UK dossier on Iraq's WMD were sent back to intelligence agencies repeatedly with a request for changes.
Evidence has been distorted and the public has really been misled on issues that helped inform the decision about war and peace
Former US intelligence official
And a senior former US intelligence official has suggested that evidence against Iraq was distorted in order to justify the attack.
The British intelligence source told BBC diplomatic correspondent Barnaby Mason that Downing Street sent the draft dossier on WMD back to the Joint Intelligence Committee six or eight times with a request that the language should be strengthened.
In response, Downing Street said no pressure had been put on the intelligence services to change the document.
UK Prime Minister Tony Blair told parliament on Wednesday that no minister, official or member of his staff had tried to override the judgements of the intelligence agencies.
The Pentagon has also strongly denied suggestions that it slanted intelligence findings about the Iraqi arsenal.
Both the British parliament and the US Congress are to investigate possible abuse of intelligence information in the run-up to the war.
"Saddam Hussein's got a big country in which to hide them. Well, we'll look," President Bush said on the last stop in a hectic overseas tour which took him to Europe and the Middle East.
The first of 1,400 experts ordered to Iraq to continue the search arrived in Baghdad on Wednesday night.
In his speech, Mr Bush highlighted the fact that two mobile laboratories had been found and that the search for WMD was continuing.
The chief UN weapons inspector Hans Blix returned to the UN Security Council on Thursday to present what may be his final report before retiring at the end of this month.
He said Iraq had left "many unanswered questions" about its unconventional weapons, but this did not mean such dangerous arms still existed.
Mr Blix said it was "not justified to jump to the conclusion that something exists just because it is unaccounted for."
Experts from the UN nuclear watchdog, the International Atomic Energy Agency, are on their way to Iraq to inspect the country's largest nuclear complex following post-war looting, to determine what may be missing from it.
Greg Thielman, who was until September 2002 a top official in charge of non-proliferation and strategic affairs in the US state department's intelligence bureau, has expressed doubt over the objectivity of the US evidence presented to the world.
"Evidence has been distorted and the public has really been misled on issues that helped inform the decision about war and peace," he told the BBC's Today programme.
"Our office had the responsibility of looking at intelligence from all sources that were available to the US Government and from all agencies," he said.
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
"The way that some of the other parts of the intelligence community like the CIA packaged information and presented it to its superiors did not seem to always be the most objective."
Senior intelligence officials quoted by the Washington Post said Vice-President Dick Cheney and his most senior aide made several trips to the CIA over the past year to question analysts studying Iraq's weapons programmes and alleged links to al-Qaeda.
This put some analysts under pressure to make their assessments fit with the Bush administration's policy objectives, according to senior intelligence officials.
The visits "sent signals, intended or otherwise, that a certain output was desired from here," one senior agency official said.