Iran's president has criticised "illegal" UN Security Council sanctions against his country, in a speech to the General Assembly in New York, BBC reported.
Mahmoud Ahmadinejad said debate over Tehran's nuclear programme was "closed" and the issue was now in the hands of the UN's nuclear watchdog.
Earlier, France's president said a nuclear Iran could threaten the world.
Other issues raised by world leaders included Darfur, climate change, protests in Burma and human rights.
During a wide-ranging speech, Ahmadinejad reiterated his assertions that all of his country's nuclear activities had been "peaceful and transparent".
Iran's nuclear work would be monitored by the International Atomic Energy Agency (IAEA), its "appropriate legal path", he added.
He denounced the "arrogant" and "bullying" permanent members of the UN's Security Council, which has imposed sanctions on Iran over its uranium enrichment programme.
And he offered educational programmes to help other UN member states with their own nuclear work.
Representatives of the US and Israel were absent for Ahmadinejad's speech, in which he also repeated his verbal attacks on Israel as an "illegal Zionist regime".
Earlier on Tuesday, French President Nicolas Sarkozy said that while Iran had the right to nuclear energy, allowing Tehran to develop nuclear weapons would mean an "unacceptable risk" for regional and world stability.
There would be no world peace if the international community showed "weakness in the face of the proliferation of nuclear weapons", Sarkozy added.
But there were dissenting views, among them Nicaraguan President Daniel Ortega, who asked how the US - the only country to have used nuclear weapons - could challenge the rights of Iran and North Korea to a peaceful nuclear programme.