The President of Iran, Mahmoud Ahmadinejad has applied for a visa to visit the United States next week, the US government has said.
The application is apparently motivated by his wish to be at the nuclear Non-Proliferation Treaty (NPT) review conference.
US Secretary of State Hillary Clinton will be among more than 30 foreign ministers attending the opening day of discussions in New York.
The US says Iran is trying to build a nuclear weapon, but Tehran has denied it.
The US ambassador to the United Nations, Susan Rice, said: "My understanding is that as of today he (Mr Ahmadinejad) has filed an application for a visa."
Tehran has always claimed that its nuclear energy programme is for peaceful, civilian purposes.
But the US and five other powers - Britain, China, France, Russia and Germany - are discussing proposed new UN sanctions against Iran for its refusal to halt uranium enrichment, a key step on the road to creating nuclear weapons.