The International Atomic Energy Agency confirmed that Pakistan turned over uranium enrichment components Wednesday that could help solve one of the biggest mysteries in the inquiry on Iran's disputed nuclear program.
Centrifuge components and uranium samples were flown from Pakistan to Vienna and handed over to the IAEA at its main laboratory, where they will be compared with suspicious traces of enriched uranium discovered in 2003 in Iran.
The samples were delivered by a team of Pakistani scientists, who will cooperate with IAEA and outside experts to determine whether they match the traces found in Iran, officials with the agency said.
"Both Pakistan and the IAEA are cooperating, and testing and analysis of the samples are underway," said Mark Gwozdecky, the IAEA's chief spokesman, in a phone interview from Vienna.
Gwozdecky declined to specify what type of materials Pakistan had turned over, but a Western diplomat close to the agency said they included uranium samples and used centrifuge components from Pakistan's nuclear weapons program.
Full results of the testing are not expected until July, though preliminary findings could be ready within 10 days, said the diplomat, who spoke on the condition that his name be withheld. He said it was uncertain whether the results would be conclusive.
The IAEA, which is the United Nations nuclear watchdog, has been investigating Iran's program for 2 1/2 years.
Washington accuses the regime in Tehran of secretly trying to develop nuclear weapons, but Iran insists that its program is strictly to generate electricity.
The key issue is Iran's uranium enrichment program, which could be used to produce fissile material either for civilian reactors or weapons.
Iran voluntarily suspended enrichment activities in November and is involved in negotiations with Britain, France and Germany aimed at winning economic concessions in exchange for a permanent halt.
The IAEA has found no proof that Iran is trying to build nuclear weapons, but it has been unable to prove that the ambitious effort is strictly peaceful.
Among the most crucial outstanding issues is whether Iran secretly enriched uranium to a level that could be used in weapons, something Tehran denies.
In 2003, IAEA inspectors discovered traces of enriched uranium at several formerly secret installations in Iran, including a former watch factory. The agency said some of the traces were at weapons-grade levels.
Iran blamed the traces on contamination of the centrifuge components that it said had been purchased from unidentified middlemen. Centrifuges are used to enrich uranium.
The IAEA tracked the purchases to the global smuggling ring operated by Pakistani scientist Abdul Qadeer Khan. He later admitted selling enrichment technology and know-how to Iran and Libya. The United States says he also provided the technology to North Korea.
Enriched uranium contains specific markers that should allow experts to determine whether the suspicious uranium found in Iran came from centrifuges that were previously used in Pakistan's weapons program.
Pakistan, which is not a signatory to the Nuclear Nonproliferation Treaty, has refused to allow inspectors into its facilities and it initially balked at turning over samples and components.
Its decision to cooperate came after several weeks of negotiations with IAEA officials.
The diplomat said the IAEA did not expect the analysis to answer all its questions about the origins of the contamination because it appeared to have come from multiple sources.
"We will get some answers, but the results are expected to be inconclusive," he said.