An Iranian research center's claim that it has built a supercomputer based on AMD processors raises questions about the effectiveness of the U.S. trade sanctions against Iran -- and about where the chips came from.

Despite federal antiterrorism trade sanctions that bar the sale of US-made computer technology to Iran, a computing research center there claims to have used Advanced Micro Devices' Opteron processors to build that country's most powerful super­computer.

The Iranian High Performance Computing Research Center said in an undated announcement on its Web site that it has assembled a Linux cluster with 216 Opteron processing cores. The system will be used for weather forecasting and meteorological research, according to the IHPCRC.

It's a relatively small machine, with claimed peak performance of 860 billion floating-point operations per second. In comparison, the last two systems on the latest Top500 list of the world's fastest supercomputers were benchmarked at 5.9 trillion operations per second.

But the fact that the IHPCRC obtained the Opterons has put a spotlight on AMD as well as a distributor of its products in the United Arab Emirates and the UAE as a whole.

A group of photos that was posted on the IHPCRC's Web site, apparently showing workers assembling the supercomputer, included one with two stacks of boxes in the background. Each of the boxes had the word "Thacker" and the initials "U.A.E." handwritten on its side.

Until this month, " Thacker/ Sky Electronics" was listed on AMD's Web site as an authorized distributor in the UAE. Thacker FZE and Sky Electronics, whose managing director is named Manoj Thacker, are related companies. But AMD deleted their listing from its site after a version of this story was posted on Computerworld.com on December 6.

An AMD spokesman said last week that the distribution deal with Thacker/Sky was terminated in July but that the companies were left on the list of distributors because of "an oversight on our part." Even now, though, Sky Electronics identifies itself as an AMD "partner" on its Web site and includes AMD processors among the products it sells.

AMD said in a written statement that it "has never authorized any shipments of AMD products to Iran or any other embargoed country, either directly or indirectly." The company added that all of its authorized distributors "have contractually committed" that they will comply with US export-control laws.

Anil Clifford, a spokesman for Thacker and Sky Electronics in the emirate of Dubai, said that the companies don't have any customers in Iran. "It is an embargo [situation] for us," he said. But goods can be imported into Iran by many different means, Clifford added. "There are a lot of Iranians in Dubai," he said. "They might buy locally from here one or two pieces and take [them] to Iran."

Michael Izady, an adjunct professor of Middle Eastern and Western history at Pace University in New York, said via e-mail that "much of what Iran gets in computer parts and advanced devices are brought in - licitly or illicitly - from the UAE."

Products may change hands many times before they get to their ultimate destinations, noted Christopher Wall, an international trade attorney at Pillsbury Winthrop Shaw Pittman . As a result, the trade sanctions against Iran are "extremely difficult to enforce," Wall said. "The rules are very easy to get around."

A spokesman for the US Department of Commerce , which enforces the export control laws, declined to comment on whether it plans to investigate how the Opterons got to Iran.

Attempts to reach officials at the IHPCRC were unsuccessful. The supercomputer photos appeared to have been removed from the center's Web site last week, although it wasn't clear whether that was related to the controversy or part of an ongoing site redesign.