Iran has agreed in principle to renew a freeze of sensitive nuclear activities in order to ease international pressure ahead of a UN nuclear watchdog meeting next week, diplomats said Tuesday in Vienna.

Details of the deal were not immediately clear and have yet to be finalized. But diplomatic sources said it would include halting production, testing and assembly of centrifuges.

Iran said last weekend that it would "come back to the suspension of some nuclear activities. IAEA Chief Mohamed ElBaradei is trying to work out the details with the Iranians," said an International Atomic Energy Agency (IAEA) official.

Iran's ambassador to the United Nations in Vienna, however, would neither confirm nor deny this information. Iranian officials were not yet available for comment.

Iran pledged last year to suspend all enrichment-related activities but has since resumed building centrifuges.

Tehran said last week that it would process 37 tons of raw uranium into uranium hexafluoride, the feed material for centrifuges that can enrich uranium for use in power stations or nuclear bombs.

The United States says Iran's uranium enrichment program is aimed at making material for nuclear weapons. Iran denies the charge, saying it is only interested in generating electricity.