ran is not opposed to sending its low-enriched uranium (LEU) abroad but wants 100% guarantees of receiving higher-enriched fuel in return for a medical research reactor, the Foreign Ministry said on Tuesday.

The ministry's comments signalled a softening of Iran's position on a UN-drafted nuclear fuel deal meant to allay Western concern about its atomic ambitions, after foreign minister Manouchehr Mottaki last week appeared to reject the proposal.

Major powers on Friday urged Tehran to reconsider and to accept the proposal. US president Barack Obama has warned Iran of more sanctions.

"Nobody in Iran ever said that we are against sending 3.5%-enriched uranium abroad," Foreign Ministry spokesman Ramin Mehmanparast said.

"If we say we are looking for 100% guarantees, it means that we want 3.5% enriched uranium to be sent out under such circumstances that we make sure that we will receive the 20% fuel," he told a news conference.

Iran's top nuclear negotiator, Saeed Jalili, said, according to Iran's Arabic-language al Alam television: "The Islamic Republic of Iran needs objective guarantees for exchanging fuel for its Tehran reactor."

Western powers agree that Iran has the right to develop a civilian nuclear programme, but want restrictions to prevent Tehran from developing a nuclear weapon and say it has been caught building nuclear facilities in secret. Iran insists its programme is for civilian purposes only.