"No proposition will make us give up the enrichment cycle," Ali Agha Mohammadi told the the student news agency ISNA.

"We won't give up this right even if (the Europeans) give Iran every economic, political and security assurance."

Britain, France and Germany have promised to come up with a proposal by the end of this month that could make or break a lengthy diplomatic process aimed at easing widespread fears Iran is seeking nuclear weapons technology.

For his part, chief negotiator Cyrus Nasseri told ISNA that if the eventual European offer does not include recognition of Iran's right to enrich, "we will not be able to consider it".

"Any decision to resume enrichment will be taken after considering the European proposals," he added.

The negotiations were on the verge of collapsing in May, but Iran, which temporarily suspended enrichment in November as a sign of good-will ahead of the talks, agreed to wait for the so-called EU-3 to come up with a proposal.

The three European powers have promised to come up with an outline for a long-term accord by the end of this month, and their proposal could make or break the talks.

They have threatened to support longstanding US demands that Iran be taken before the UN Security Council for discussion of possible sanctions if it resumes enrichment.

Mohammadi said "our wish is to reach an understanding with the Europeans."

But he added that "our main objective in the negotiations is to preserve the fuel cycle, so it is unimaginable abandoning that principal objective and agreeing to anything else."

Washington accuses Tehran of using a civilian atomic energy program as a cover to seek nuclear weapons and seeks a permanent halt to uranium enrichment and plutonium reprocessing activities that could be used in an arms program.

Iran denies the charge and says it has the right under the nuclear Non-Proliferation Treaty to the peaceful use of nuclear technology, including making atomic fuel.

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