The US official leading the hunt for Iraqi weapons of mass destruction says it is still too early to confirm whether Saddam Hussein had them or not.
Duelfer, appointed in January by the CIA, leads a force of over 1,000
Charles Duelfer said he was still getting reports that weapons had been hidden, but that the search was proving more complicated than anticipated.
He said his Iraq Survey Group also had
millions of documents to analyse.
Mr Duelfer's predecessor David Kay resigned two months ago saying he no longer believed any WMD would be found.
Mr Duelfer was speaking in Washington where he was appearing before Senate committees.
"The picture is much more complicated than I anticipated going in," he told reporters.
He added: "We do not know whether Saddam was concealing WMD in the final years or planning to resume production once sanctions were lifted.
"We do not know what he ordered his senior ministers to undertake. We do not know how the disparate activities we have identified link together."
Mr Deulfer, who testified to the Senate Armed Services Committee behind closed doors, said in a prepared statement that the search by the ISG had been hampered by the "extreme reluctance" of Iraqi scientists to speak freely and the difficulty of sorting through millions of documents.
The Associated Press reported that Mr Duelfer told the committee that the ISG had found new evidence that Iraqi scientists flight tested long-range ballistic missiles and unmanned aerial vehicles that "easily exceeded" UN limits of 93 miles.
And the survey group has new information indicating the regime engaged in ongoing research to produce chemical or biological weapons on short notice, using civilian - or "dual use" - facilities, AP reported.
The BBC's Adam Brookes, in Washington, says Mr Duelfer is taking a more cautious approach than his predecessor.
Mr Duelfer described his mission as going way beyond the search for actual stockpiles of chemical and biological weapons; he said he intended to discover the intentions and capabilities of Saddam Hussein's regime to develop those weapons.
Our correspondent says this echoes the Bush Administration's justification for the invasion of Iraq: even if Saddam Hussein did not possess actual weapons, he retained the capability to make them.