Tehran: Iran is studying proposals from the United States, Russia and France on a nuclear fuel swap, after Tehran said last week that it was stepping up its own uranium enrichment, an official said on Monday.

It was not clear how far the proposals referred to by Ali Akbar Salehi, the head of Iran’s Atomic Energy organisation, went beyond a deal brokered last year by the United Nations nuclear watchdog which Tehran has yet to accept.

“After Iran’s decision to internally produce 20% enriched uranium, we received some proposals from Russia, America and France and right now we are studying this issue along with other proposals from different countries,” he was quoted as saying by the semi-official news agency ILNA.

President Mahmoud Ahmadinejad said on Thursday that Iran was now able to enrich uranium to more than 80% purity, close to levels experts say would be needed for a nuclear bomb, although he denied it had any such intention.

Iran had already begun this new stage of nuclear activity at its Natanz reactor, he said. Washington and its allies fear Iran wants to acquire nuclear weapons, but Tehran says its aim is to produce electricity.

Iran and the five permanent members of the United Nations Security Council plus Germany have so far failed to agree on terms for swapping uranium for enrichment outside Iran.

“These countries’ proposal will only stop Iran from enrichment when all our terms and conditions for swapping enriched uranium are observed,” Salehi said.

“From now on the continuous production of 20% fuel is on the agenda and the first 5.3 uranium capsule for injection at the Natanz facility is finished,” he added.

US secretary of state Hillary Clinton said on Sunday she saw few alternatives to more sanctions on Iran. Washington sought a peaceful end to a nuclear standoff but did not want to engage diplomatically “while they are building their bomb”, she added.

A new round of UN sanctions would require the consent of veto-wielding Security Council members Russia and China, both of which have been less inclined to impose them in the past.