A report by the United Nations' nuclear watchdog says Iran has ignored a UN Security Council call to suspend all nuclear fuel enrichment by today's deadline and has accelerated the programme, diplomats said.
They said 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.
Iranian President Mahmoud Ahmadinejad
The report was being sent to the Security Council, which could impose sanctions against Iran.
Tehran has said its enrichment policy is irreversible and that it could withstand any consequences, whether financial penalties or military attack.
"Iran was supposed to suspend, but since they continue to do experiments, they have not suspended enrichment efforts. The information available to us shows they have not heeded the request for compliance so far," said a senior official close to the IAEA.
The report said inspectors' tests confirmed Iran's claim this month to have enriched uranium with a cascade of 164 centrifuges to the low level needed for fuelling nuclear power plants.
It must be purified to a much higher level to set off the chain reaction required for a bomb.
Iran was also building two new cascades of 164 centrifuges at its underground enrichment plant. IAEA inspectors were monitoring the construction.