US forces in Iraq claimed to have found a trailer built by the toppled government of President Saddam Hussein for use as a mobile biological weapons laboratory.
Undersecretary of Defense for Intelligence Mr Stephen Cambone stopped short of calling the big truck a "smoking gun" proving US charges that Iraq produced weapons of mass destruction.
He told reporters sophisticated production equipment had been found inside the vehicle but no germ agents.
It was the first time US officials have said they have found firm evidence of such an Iraqi weapons programme, which was cited before the war as a justification for the invasion to oust Saddam.
The trailer was found on April 19th in northern Iraq and will soon be taken apart and minutely examined in Baghdad, Mr Cambone told a Pentagon briefing.
Mr Cambone said the "mobile production facility," painted military green, was similar to 18 that the US believes the former Iraqi government built.