Uranium talks are 'last chance' for Tehran

Western powers are to set two demands, including the closure of Iran's best-protected uranium facility, when negotiations over the country's nuclear programme resume this week.

The United States and its European allies will also tell Iran that it must stop refining uranium to a concentration of 20%, a level considered a short step away from weapons grade, and move existing stocks of fuel already enriched to such levels abroad.

The demands signal a Western acceptance of the most important conditions that Israel says must be fulfilled if it is to be persuaded to drop its threat of uni-lateral military action against Iran's nuclear facilities.

President Barack Obama has warned Iran that the talks, which begin on Friday, represent its "last chance" for a diplomatic resolution to the crisis.

Iranian media said the talks, which collapsed more than a year ago, would be held in Istanbul, apparently dropping a push by Tehran to stage the talks in a new venue.

Western diplomats have been quoted as saying that Iran will be told it must seal and ultimately dismantle its Fordow uranium enrichment plant, buried deep inside a mountain near the holy city of Qom, as a sign of its sincerity.

Iran has begun enriching uranium to 20% at Fordow and is moving much of its nuclear fuel to the plant. This has alarmed Israel, whose US-provided "bunker-busting" bombs would probably not be able to destroy the facility.

Iran says it plans to triple its stocks of the higher-grade fuel for a research reactor that produces medical isotopes.