The world's nuclear watchdog has said in a report that Iran has ignored a UN Security Council call to suspend all nuclear fuel enrichment and has accelerated the programme.
The report by the International Atomic Energy Agency (IAEA) also said Iran had done little during a 30-day grace period to answer questions meant to determine whether its nuclear activity is solely for civilian purposes.
The report will be sent to the security council which could eventually impose sanctions on Iran.
Tehran has said its enrichment policy is irreversible. It has vowed to withstand any consequences, whether financial penalties or military attack.
Just hours before the report was circulated, Iranian President Mamoud Ahmadinejad said that his country will pay no attention to international demands that it call a halt to its nuclear programme.
Mr Ahmadinejad said that Iranians would ignore UNSC resolutions calling for an end to its controversial uranium enrichment work.
The US Secretary of State, Condoleezza Rice, said the credibility of the security council was at stake over Iran's nuclear programme.
Speaking at a meeting of NATO Foreign Ministers in the Bulgarian capital, Sofia, Dr Rice said the will of the UNSC should not be ignored.
