Iraq's former anti-corruption chief has given further details of what he says is widespread abuse in his country.
Iraqi reconstruction has been marred by corruption, reports say
Radhi Hamza al-Radhi told the BBC that the commission he headed had gathered evidence of 3,000 cases of corruption.
He was speaking in Washington, where he fled earlier this year, saying he feared for his life.
A former judge charged with leading the fight against corruption in Iraq, he accused the Baghdad government of stopping him from pursuing culprits.
Mr Radhi told the BBC he had uncovered corruption on a huge scale.
"We started our job in June 2004 with 3,000 cases," he said. "And we found that $18bn was missing."
The former commissioner said the Iraqi government had frustrated his efforts.
He said members of his staff and their families had been targeted - some of them abducted, tortured and killed.
Earlier this month Mr Radhi told a US congressional committee that Iraqi Prime Minister Nouri Maliki had protected some relatives involved in corruption.
However the Iraqi government has accused Mr Radhi himself of wrongdoing, and said it would file corruption charges against him.
Mr Radhi has described those allegations as a smear campaign.
There have been numerous reports on corruption in Iraq.
In July, the US agency overseeing reconstruction in Iraq said economic mismanagement and graft were endemic, and equivalent to "a second insurgency".