It was placed under the control of the International Atomic Energy Agency (IAEA).

Enrichment process

Yellow cake uranium is not strong enough to power an electricity station or nuclear weapon until it is re-processed and enriched.

But Cameco, a company in Canada, is now going to process the yellow cake in a deal worth tens of millions of dollars.

An Iraqi government spokesman said Baghdad asked the US to help get rid of the uranium because of its potentially harmful effects.

The shipments cost the US about $70m, but the Iraqi government has pledged in principle to repay some of the costs, Whitman said.

Arrangements for the sale began several months ago, but the transfer itself took "weeks not months", he said.

Deal questioned

The shipment came after Cameco responded to a bid request made last year by the US government, Lyle Kharan, a spokesman for the company, said.

"We are satisfied at having been able to remove uranium from one of the most unstable regions of the world, and to have transfered it to a stable region to produce our own electric power," he said on Sunday.

He said the yellow cake would be used at the Blind River and Port Hope nuclear power plants north of Toronto.

But Gordon Edwards, a spokesman for the Coalition for Nuclear Responsibility, told Al Jazeera that some questions regarding the transfer have not been answered.

"One has to wonder why the secrecy? I think it is probably because of the origin and therefore the symbolic importance of it - not because the material itself could be used for any nefarious purpose," he said.

"[Cameco] bought [the yellow cake] at cheaper prices than world market prices and one has to wonder whether this was a smart deal for the Iraqis.

"Instead of selling it to Cameco, which is more or less a wholesaler, they could have instead had a bidding process that involved the utilities - and they probably would have gotten a better price for it."