Al-Alam TV, a state-owned Arabic channel in Iran, reported that Tehran had delivered its response to the draft deal on Thursday, which has already been officially backed by the US, Russia and France.

But the IAEA has not yet confirmed the report.

The pact was designed to help allay fears from Western nations that believe Iran intends to build nuclear weapons - a charge Tehran denies.

'Buying time'

Local media have said Tehran will accept the framework of the deal, but also demand changes to it.

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Javan, a pro-government newspaper, reported that Iran will seek two changes to the plan.

They include, it said, the gradual shipment of its low-enriched uranium abroad, instead of sending it in one go, and a "simultaneous exchange" of nuclear fuel to a Tehran research reactor in return for its shipment of uranium.

Nazanine Moshiri, Al Jazeera's correspondent in Tehran, said it appears that Iran will "not give up its right to enrich uranium but it is willing to co-operate on an exchange".

She said this move would allow Iran to "buy time".

"Iran will still continue to produce enriched uranium at its Natanz plant, whatever it sends out they'll be able to replace very quickly, and if it sends anything out it will get highly enriched uranium replaced at the same.

"So in a way Iran is not really giving an inch on this at all." 

Iran's formal proposal is expected to be handed over to the IAEA in Vienna, Austria.

Nuclear inspection

It comes as a team from the IAEA returned to Vienna after inspecting a controversial nuclear plant near the Iranian town of Qom.

Last month's disclosure over the Qom plant added to international concern over Iran's atomic programme.

Iran has already been enriching uranium - the most controversial aspect of its nuclear project - for several years at another plant in the central city of Natanz, in defiance of three sets of UN sanctions.

Enriched uranium produces fuel for civilian reactors, but in highly extended form can also make the fissile core of an atomic bomb.