VIENNA - Iran wants more talks on a U.N.-drafted nuclear deal because it needs guarantees it will receive reactor fuel, a senior official said Monday, adding to doubts that a standoff with big powers can be ended soon.

Western powers have urged Iran to accept a draft deal in which it would send most of its low-enriched uranium (LEU) abroad by the end of the year for further enrichment to turn it into fuel for a medical reactor in Tehran.

Iranian Ambassador Ali Asghar Soltanieh told Reuters more talks were needed in order to ensure that our technical concerns, and especially the issue of the guarantee of the fuel supply, are taken into consideration.

Tehran appears to be stalling after seeming ready to make concessions to an international community that is threatening to impose more sanctions over fears that Iran is developing nuclear weapons.

Iran says its uranium enrichment program is for peaceful electricity generation only. Senior lawmakers have voiced deep misgivings about parting with the bulk of Iran's LEU, seen as a strategic asset and a strong bargaining chip.

We are ready for the next round of technical discussions in Vienna at the IAEA headquarters, Soltanieh said by telephone, adding that the International Atomic Energy Agency -- the U.N. nuclear watchdog -- should now arrange a suitable date.

The IAEA had no immediate comment.

NEW SANCTIONS?

Western powers have signaled that their patience is limited and they will consider new sanctions early next year if Iran does not make its nuclear work more transparent.

The IAEA draft plan, backed by the other participants -- the United States, Russia and France -- aims to reduce Iran's LEU stockpile below the minimum quantity that could be turned into the highly enriched uranium needed for a nuclear bomb.

We are ready to buy the fuel from any supplier under the full scope of safeguards and surveillance of the IAEA, said Soltanieh, Tehran's veteran ambassador to the IAEA.

The core issue is the assurance and guarantee of the supply, keeping in mind the past confidence deficit where we did not receive the fuel we had paid for, he said, alluding to supply deals that fell through after the Islamic Revolution.

Iran's foreign minister told reporters in Kuala Lumpur that Tehran wanted the IAEA to establish a technical commission to review the draft deal. He said Iran would continue with enrichment for its own needs.

Iran gave the IAEA an initial response to the draft deal Friday after talks in Vienna on October 19-21 with the three big powers. Diplomats say IAEA chief Mohamed ElBaradei told Tehran to come back with a full answer and better proposal.

Britain's foreign secretary urged Iran to answer quickly.

We both want to see a prompt response from the Iranian regime in respect of the Tehran research reactor proposal, David Miliband told reporters after talks with Russian Foreign Minister Sergei Lavrov in Moscow.

Western diplomats say Iran has asked to receive fuel for a Tehran reactor making radio-isotopes for cancer treatment before shipping out any of its own LEU. Iran also wants to transfer the enriched uranium in small tranches, not in one go.

Diplomats say the Iranian demands are unacceptable because the deal in this form would not lessen Iran's potential to turn LEU to yielding bomb-grade nuclear fuel if it wanted, a scenario the West fears due to Iran's history of nuclear secrecy.

The messages from Tehran are negative, I am quite pessimistic, one European diplomat said.

Soltanieh said the talks were a historic moment.

(This is an) opportunity for the IAEA to realize its statutory role and also for the potential fuel suppliers to prove their political will to enter into technical cooperation for such humanitarian projects under the auspices of the IAEA.

(Additional reporting by Mark Heinrich in Vienna, Conor Sweeney in Moscow and Razak Ahmad in Kuala Lumpur; Editing by Kevin Liffey)

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