APIranian technicians, work with foreign colleagues at the Bushehr Nuclear Power Plant, just outside the southern port city of Bushehr (File).

The West offered Iran a draft nuclear deal under the International Atomic Energy Agency last November. It calls for Iran to trade about 80 percent of its domestically produced low-grade uranium for more highly enriched nuclear fuel from France and Russia.

Iran presented a counter-proposal late last year under which it would trade its low-grade uranium for the more highly enriched variety, but only on its soil, and not all at one time. Iran has given Western powers until the end of January to accept its counter-proposal.

Iranian officials have repeatedly insisted their nuclear program is for peaceful, civilian purposes, but the West suspects Tehran is working to produce atomic weapons.

Secretary of State Hilary Clinton recently warned Tehran the international community will "not back down" in the face of its defiant refusal to accept the IAEA draft nuclear deal. Western powers are discussing possible new economic sanctions on Tehran.