The change is being caused by the expiration of the HEU-LEU contract, signed in 1993 by Russia and the US. The treaty, which expires in 2013, allowed the duty-free export of Soviet uranium extracted from nuclear warheads.

FORBES: Forget Gold and Oil, Buy Uranium!

Iran has made much in the past of this civil use for its 19.75% LEU, arguing that it is running out of its original imported stock from Argentina (it now has enough to fuel the TRR for over eight years) which it needs for the treatment of cancer patients.

ECONOMIST: Iran and nuclear weapons

It also says that Iran has boosted its stockpile of low-enriched uranium (LEU) by 500kg to more than 1, 300kg in the last six months.

BBC: Uranium found at second Syria site - IAEA

The best way to ease those immediate fears would be to halt Iran's accumulation of 19.75% LEU. Mr Jalili and his team might agree to a temporary suspension in return for some immediate relief on sanctions, say an EU promise to suspend the oil embargo.

ECONOMIST: Iran and nuclear weapons