The United Nations has said Iran has admitted to misleading the UN over its experiments with producing plutonium.
Iran had first told the International Atomic Energy Agency (IAEA) its last experiments with the reprocessing of plutonium took place in 1993 but revised that date to 1998, according to a draft of a speech deputy IAEA chief Pierre Goldschmidt is due to make today.
The document said the IAEA had asked Iran to confirm that one bottle of a solution containing plutonium "had been processed in 1995 while the solution in the second one had been purified in 1998".
"In a letter dated May 26th, 2005, Iran confirmed the agency's understanding with regard to that chronology," the speech said.
This revelation will likely add fuel to Washington's belief that Iran's nuclear energy programme is a cover to develop a nuclear bomb. Iran denies the accusation, insisting its nuclear ambitions are limited to the peaceful generation of electricity.
Diplomats on the IAEA board said this was another breach of Iran's obligation to provide a full and accurate declaration of all sensitive nuclear materials in the country as required by the 1970 nuclear Non-Proliferation Treaty.
Mr Goldschmidt's speech will say Iran had not provided all documentation related to shipments of equipment used to enrichment uranium sold to Iran by black marketeers. Also, some of the documents Tehran did provide contradicted previous information it had given the IAEA, he says.
Access to these documents "is essential for verifying the completeness of Iran's declarations concerning such (uranium enrichment) equipment", the speech said.