"Iran has become a nuclear country and atomic Iran will not back down," Ahmadinejad said.

"They cannot hurt us, not that they don't want to but because they are incapable of doing do as they are in a difficult situation."

Ahmadinejad said "the global arrogance cannot stop the Iranian nation", in an allusion to the United States which has never ruled out military action to stop Iran's nuclear drive.

The UN Security Council has already imposed two sets of sanctions against Iran after it failed to heed ultimatums to suspend uranium enrichment, the process that makes nuclear fuel but in highly extended form can also produce the fissile core of an atomic bomb.

The West fears that Iran's nuclear programme is cover for a push to develop the bomb, although Iran has said repeatedly that it is for civilian purposes only.

The Iranian president said that a petrol rationing plan introduced by the world's fourth largest oil producer on Wednesday gave it even greater immunity from international pressure.