"I have now heard three times in the last week, from separate sources that I have been talking to, that something big is being planned for Baghdad," Ijaz told Fox News "Special Report" host Brit Hume on Tuesday.

"The idea that is being put forward is to kill as many as 3,000 to 5,000 people at one shot – something that would be similar to a World Trade Center type of attack," he said.

Ijaz, who in December 2001 blew the lid off the Clinton administration's decision not to accept multiple offers for Osama bin Laden's extradition to the U.S., detailed the accounts of Kurdish sources, who say they intercepted a convoy carrying suspicious cargo.

"About three days ago in the northern part of Iraq," said Ijaz, "a convoy of trucks and jeeps and cars was brought across from Iran, where some of the Kurdish Peshmerga [are]. ... They intercepted one of those trucks that were carrying a large warhead that had extremely sophisticated plastic – C-4 plastic explosives in it."

Ijaz said that once interrogated, the driver admitted that there were a total of 30 warheads that were scheduled to be imported to Iraq from Iran.

"We are told now that somewhere between six and 12 of them may have, in fact, been laden with chemical explosives that would be then attached to a rocket of some sort inside Iraq that's already there in a separate convoy."

The whereabouts of both convoys is currently unknown, said Ijaz.

How credible are his sources?