The US Secretary of State, Condoleezza Rice, has indicated that Iran faces possible sanctions if it does not comply with UN directives on its nuclear programme.
Ms Rice said she was certain that the UN Security Council would look at measures to ensure that Iran had no choice but to comply.
Her remarks follow growing international concern over Tehran's announcement that it has managed to produce enriched uranium.
She suggested that chapter seven of the UN Charter may be used to impose sanctions. It sets out that specific action can be taken when there is a threat to international peace or an act of aggression. It allows for sanctions, including economic and transport measures, or the severance of diplomatic relations.
Several resolutions against Iraq, adopted by the UNSC before the US-led invasion of March 2003, were taken under chapter seven.
Iran says it only wants to generate atomic energy, but it is feared enrichment could be extended to make nuclear warheads.
IAEA chief, Mohamed ElBaradei, said talks on the demand to freeze uranium enrichment would continue, although Iran is showing no sign of any readiness to compromise.
Representatives of the five permanent members of the Security Council and Germany are to meet in Moscow next Tuesday to discuss the crisis.
