The FBI is conducting the tests on a small number of employees who had access to the intelligence on Iran's spy communication system, the New York Times said Thursday.
U.S. intelligence officials have said Chalabi informed Iran the United States had broken the secret codes used by Iranian intelligence to transmit confidential messages to posts around the world.
Wednesday, Chalabi's lawyers made public a letter they sent to Attorney General John Ashcroft and FBI Director Robert Mueller repeating Chalabi's denials and demanding the Justice Department investigate the disclosure of the accusations against him.
Additionally, Richard Perle, the former chairman of the Defense Policy Board and a long-time Chalabi supporter, said the notion Chalabi would compromise the U.S. code-breaking operation "doesn't pass the laugh test."
Perle said it was more plausible the Iranians, knowing already the United States was reading their communications, planted the damning information about Chalabi to persuade Washington to distance itself from him.