Downing Street has said it will wait and see whether the Iraq Survey Group (ISG) turns up evidence of weapons of mass destruction (WMD).
No WMDs have been found in Iraq
The comments came in response to George W Bush saying he wants the facts about why no weapons have been found.
Tony Blair has been urged to admit the intelligence he presented to Parliament on Iraq was "wildly wrong".
"It's getting embarrassing to watch our government still trying to deny reality," said Robin Cook.
The former foreign secretary said Mr Blair should confess that while he believed information on Iraq's weapons "in good faith", it was wrong.
The US president said: "I want to know the facts [about WMD] I want to compare the ISG finds with what we thought."
That came after the White House conceded its intelligence reports on Iraq might have been wrong.
Mr Blair is due to be questioned over intelligence on Iraq's WMD when he makes his regular appearance before the influential Commons liaison committee of select committee chairmen on Tuesday.
Condoleezza Rice, the US's national security advisor has given a round of interviews in which she acknowledges possible flaws in pre-war intelligence.
She told NBC television's Today show: "What we have is evidence that there are differences between what we knew going in and what we found on the ground."
Her remarks follow former senior US weapons inspector David Kay's claims that intelligence that Iraq possessed stockpiles of chemical and biological weapons were false.
Mr Cook said: "Now that even the White House has admitted they may have got it wrong, it's embarrassing to watch our government still trying to deny reality. The game is up.
"Even David Kay, recent head of the Iraq Survey Group, has told us that the hunt has been sufficiently intense to conclude that there were no weapons of mass destruction.
"Now that Lord Hutton has cleared Tony Blair of lying, he is in a strong position.
"He will never have a better opportunity to say that he believed in all good faith the intelligence he was given and he gave to Parliament, but that it has turned out to be wildly wrong.
Ex-foreign office and defence minister Doug Henderson has urged the government to "clarify its position".
"Does Britain now accept, as the US government now seems to believe, that weapons of mass destruction will not be found?"
Blair in best position to explain
Shadow foreign secretary Michael Ancram also called on Tony Blair to explain why he still believed the WMD intelligence and pressed for an independent inquiry into the lead up to the Iraq war
"It seems that Tony Blair is the only person still certain that weapons of
mass destruction will definitely be found. He must explain why he is the odd man
out and produce the evidence as to why," he said.
Wait and see
But the inquiry calls were brushed aside by Mr Blair's official spokesman, who said the Iraq Survey Group should be allowed to complete its work.
He said: "The prime minister has said that he did believe the intelligence was right and he did believe there would be an explanation.
"What Condoleezza Rice actually said was we should wait for the facts. The
process hasn't yet been completed. The ISG is still pursuing its work and we
should wait for that."