The United States is open to holding talks with Iran designed to revive a nuclear swap deal and is hopeful that such a meeting, which would include other world powers, could take place in the coming weeks, the US State Department said Wednesday.

Iran sent a letter Monday to the United Nations nuclear monitoring body, known as the International Atomic Energy Agency (IAEA), signalling an interest in renewing the discussions.

'We obviously are fully prepared to follow up with Iran on specifics regarding our initial proposal involving the Tehran research reactor,' State Department spokesman PJ Crowley said.

Under the deal originally proposed in October, Iran would ship some of its enriched uranium out of the country in return for nuclear fuel for the Tehran reactor. The proposal is meant to build confidence that Iran is willing to address questions about the nature of its nuclear activities.

Iran rejects Western allegations that its nuclear work is intended for weapons, saying it is purely for generating energy.

The proposal was backed by the five permanent members of the UN Security Council - Britain, China, France, Russia and the United States - plus Germany. European Union foreign policy chief Catherine Ashton has led negotiations with Iran on behalf of the six countries.

Iran did not outright accept the offer, prompting the Security Council to enact sanctions in June, followed by sanctions from the United States, European Union and Canada.

Crowley said the United States is currently evaluating the latest Iranian proposal contained in the letter to the IAEA. He added that Iranian proposals are usually 'heavily conditioned'.

'We have clearly indicated to Iran on a number of occasions our willingness to engage,' he said.