The Bush administration has rejected charges that there were serious failings in its intelligence-gathering before the war in Iraq.
The CIA has been accused of using intelligence from 1998
The Central Intelligence Agency (CIA) has been accused of using old information, in a letter from members of the House of Representative's intelligence committee.
The criticism was dismissed as "absurd" by CIA spokesman Bill Harlow.
And President Bush's National Security Advisor Condoleezza Rice said: "I just don't think that was plausible."
"We did not have perfect foresight into what we were going to find in Iraq," she told Fox News on Sunday.
But the Republican chairman of the House intelligence committee and its top-ranking Democrat said the CIA had failed to challenge assessments made in 1998 of the threat from alleged Iraqi weapons of mass destruction.
The leaked letter comes as the UK and US governments are facing mounting questions over the evidence used to justify war.
In it, Porter Goss and Jane Harman said the CIA had relied on old intelligence dating back to 1998 along with "some new 'piecemeal' intelligence" when formulating its reports on Saddam Hussein's weapons programmes.
"The assessment that Iraq continued to pursue chemical and biological weapons remained constant and static over the past 10 years," the letter said.
But the CIA said the intelligence committee had not yet taken the time to evaluate fully how its assessment was made.
Members of the committee have spent four months looking at 19 volumes of classified material used by the Bush administration to make its case for war.
"The intelligence community stands fully behind its findings and judgements," said the CIA spokesman.
"In the post-1998 time period the intelligence community launched an important and sustained effort to enhance our unilateral understanding of Iraq and its weapons of mass destruction programmes.
"From all of our disciplines, important gains were made."
Condoleezza Rice said she knew "nothing" of any White House role in the leak of the identity of a CIA officer linked to investigation of alleged Iraqi uranium procurement.
Joseph Wilson, a former US ambassador, was sent by the CIA to Niger to see if there was any truth in claims that Saddam Hussein had purchased uranium there.
Rice: "No such White House effort"
He reported that it was highly unlikely.
On Sunday the Washington Post said that two White House officials had revealed that Mr Wilson's wife was undercover CIA operative.
Such a disclosure, if made, could be illegal.
"I know of no such White House effort to reveal any of this," said Condoleezza Rice.
"It is well known that the president of the United States
does not expect the White House to get involved in such things,
anything of this kind," she added.