Investigators following up on a nuclear sting in eastern Europe suspect that a crime syndicate was trying to sell weapons-grade uranium to buyers in North Africa.
Officials in Moldova, a former Soviet republic, told The Associated Press that 1 kilogram (2.2 pounds) of highly enriched uranium remains in criminal hands and is probably in another country.
Though that is a fraction of what is needed for a bomb, the investigation has provided fresh evidence of a black market in nuclear material probably taken from poorly secured stockpiles in the former Soviet Union.
U.S. authorities have been aiding the Moldovans in the international search for a Russian believed to be the ringleader of the smuggling operation. They also are searching for a North African man who they believe attempted to buy the uranium in Moldova before fleeing the country.
Neither suspect has been publicly identified. The North Africa link, though, has worried officials because terrorist groups such as al-Qaida in the Islamic Maghreb are in the region. The concern is raised in a report prepared by the staff of Sen. Richard Lugar, the top Republican on the Senate Foreign Relations Committee.
"Should the existence of a legitimate buyer (or middleman) from a region with a history of terror cells be confirmed, then the case would be substantially more alarming than other recent fissile material interdictions, where official agents were the sole potential buyer," said the report, which was obtained ahead of its release Tuesday.
The AP has learned details of the investigation from the report and from U.S., United Nations and Moldovan officials. Some of the officials spoke on condition of anonymity because of the sensitivity of the investigation.
Moldovan investigators, who had been trained by U.S. specialists, set up a sting in June after learning of the ring operating out of the breakaway Republic of Transnistria. Undercover police bought the small quantity, pre-empting the North African buyer.
They arrested six people and seized 4.4 grams (0.16 ounces) of uranium that had been offered as a sample at a price of 420,000 euros, or $600,000. The sellers claimed to have 9 kilograms (20 pounds) more as well as a quantity of plutonium, according to Lugar's report. The group wanted 23 million euros (nearly $31 million) for the larger quantity of uranium, which would have been about one-third of the material necessary to build a crude nuclear weapon.
It is not known whether the group had access to that much uranium. But Moldovan prosecutors, who have interrogated the arrested suspects extensively, say they believe that the group still has at least a smaller quantity.
"Members of the ring, who have not yet been detained, have 1 kilogram of uranium," which is in another country, said Maria Vieru, a spokeswoman for Moldovan prosecutors.
According to U.S. and U.N. officials, the sample of uranium oxide was traced to specific Russian enrichment facilities and was matched later with at least one earlier seizure of uranium. Nuclear forensic experts can analyze chemical traits of uranium and other radioactive material, which can provide a kind of nuclear fingerprint that can be traced to known stocks.
According to Olli Heinonen, a former investigator at the International Atomic Energy Agency, a small quantity of uranium oxide enriched to bomb-grade level could have come from Russian civilian nuclear stocks used in research reactors. But if the smugglers indeed have the larger quantity they were offering, it would signal that criminals had gained access to military stocks.
Moldovan authorities believe the uranium was taken through Transnistria, which is known to be a haven for smugglers. The report by Lugar, who has spearheaded U.S. efforts to secure weapons of mass destruction around the world, says flights into Transnistria cannot be monitored, and the borders between the breakaway territory and Moldova proper as well as Ukraine are porous. The report also warns that action needs to be taken to improve security at Russian nuclear facilities.
The offer of plutonium, if legitimate, also was particularly troubling, because less plutonium is needed to make a nuclear bomb. Unlike highly enriched uranium, plutonium can be combined with conventional explosives to make a toxic dirty bomb that could spread radioactivity over a wide area.
The investigation widened following the arrests when Moldovan authorities searched the office of one of the detained men, a lawyer in the country's capital, Chisinau.
Data found on a computer revealed the group had sought contacts in North Africa for the sale. The police also seized photocopies of passports, including those of the North African and Russian men being sought.
Little is known about the North African man, except that he was believed to be married to a Moldovan woman and fled the country. Officials familiar with the investigation would not say which country he came from.
U.S. authorities have been pressing Russia for help in the investigation. The Russians "are taking appropriate action," said White House national security spokesman Tommy Vietor.
The Russian government had no immediate comment on the new details of the investigation.
Associated Press writers George Jahn in Vienna and Corneliu Rusnac in Chisinau, Moldova, contributed to this report.
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The Senate report can be found at http://wid.ap.org/documents/np-minority-report.pdf