President Mahmoud Ahmadinejad said today Iran was about to take the "final step" in a nuclear programme that the UN has called on it to curtail.
Mr Ahmadinejad did not say what the final step was, but he repeated comments he made this week that Iran would celebrate its "right to nuclear technology" by March, the end of the Iranian year, the official IRNA news agency reported.
Tehran, which says its nuclear aims are peaceful, faces possible sanctions for ignoring UN demands to halt sensitive atomic work, but there is no agreement at the UN Security Council on any penalties.
Analysts say this may be encouraging Iran in its defiant stance.
In reported comments, the president said: "This path that Iran has chosen is irreversible, and big powers should not make useless efforts to prevent the Iranian nation from moving forward."
Analysts say the defeat for President Bush's Republican Party in last week's congressional elections may also have buoyed Iran, even though it remains wary of the victorious Democrats, who are seen in Tehran as close to arch-foe Israel.