The US has said Iran continues to mislead the United Nations nuclear watchdog about its past and present nuclear activities.
US Ambassador Jackie Sanders said it is evident that Iran has not come clean about its past or present nuclear activities.
Mr Sanders told a meeting of the International Atomic Energy Agency, which had just heard an IAEA report on Iran, that the continuing contradictions between Iran's declarations and the facts as they are uncovered cannot be explained by inadvertent error.
'They are simply too numerous and pervasive,' he said.
Meanwhile, IAEA deputy chief Pierre Goldschmidt told the meeting in Vienna that Tehran had admitted to misleading the IAEA about secret experiments.
He said Iran had admitted carrying out plutonium experiments as late as 1998, five years later than it had previously stated the experiments had ended.
Commenting on the revelation, former Bush administration adviser Richard Perle said pressure on Tehran was now needed from the international community.