Ahmadinejad has been a strong backer of Iran's nuclear programme

Iranian President Mahmoud Ahmadinejad has applied for a visa to visit the United States next week, the US says.

The application is apparently motivated by his wish to be at the nuclear Non-Proliferation Treaty (NPT) review conference starting on Monday.

US Secretary of State Hillary Clinton will be among more than 30 foreign ministers attending the opening day of discussions at the United Nations.

The US says Iran is trying to build a nuclear weapon, but Tehran denies this.

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 says 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.