The International Atomic Energy Agency says it sent a team of its inspectors to Tehran to check on the nuclear declaration that Iran gave to the agency this past week.
The IAEA said five senior inspectors were joining a team already in Iran visiting nuclear facilities and taking environmental samples. Iran has submitted what it claims to be a full dossier of its nuclear activities covering the past 20 years. The document was handed over a week before the October 31 deadline that the IAEA had given Tehran to prove that its nuclear energy program was peaceful.
The United States claims Iran is using the program to build atomic weapons.
The IAEA is checking the accuracy and completeness of the documents, and it will report its findings to its board of governors by the end of next month.
IAEA spokesman Mark Gwozdecky said scientists are also trying to trace the origins of equipment found at two sites in Iran that were contaminated with weapons-grade uranium.
"We are still investigating several possibilities. One is that the particles came from equipment that was imported. Another is that it came from domestically produced equipment, and another is a mixture of those two. We have people going in and out on a regular basis, and we have a work plan to have inspectors to continuously be in Iran through the end of the month," the spokesman explained.
Tehran maintains that the components were imported and bought on the black market, so they can no longer be traced.
Western diplomats say there must be some record of the financial transactions and want Iran to provide the IAEA with details.
The United States is not the only country concerned that Iran's nuclear program may not be as purely peaceful as Tehran claims. Australia, Canada and Japan sponsored a resolution last month calling for Iran to declare all aspects of its nuclear program to the IAEA.
With the exception of Iran, the resolution was supported by nations on the 35-member IAEA board. If suspicions remain that Iran has a possible secret weapons program, the matter could go before the U.N. Security Council for possible sanctions.