The US-led hunt for weapons of mass destruction in Iraq is making "solid progress" despite failing to find any biological or chemical weapons, US officials have said.
"We are making solid progress. And as is with most progress it is preliminary. We are not at the final stage of understanding fully Iraq's WMD [weapons of mass destruction] program or having found WMD weapons," said CIA special adviser Mr David Kay, who recently returned from Iraq.
The failure to unearth such weapons has undermined the Bush administration's credibility, critics say, but Mr Kay called for patience.
"It's going to take time. The Iraqis had over two decades to develop these weapons and hiding them was an essential part of their program, so it is not an easy task and we are not close to a final conclusion yet," Mr Kay said.
He said Iraqi scientists who were "collaborating and co-operating" and recently found documents have led the WMD hunting team to new sites in Iraq. Physical evidence has been collected, but he declined to describe it.