Six world powers holding talks with Iran on its nuclear programme said Tuesday at a meeting of the UN atomic agency that they were "deeply concerned" by Tehran's recent atomic upgrades.
"(We) are deeply concerned that Iran continues to undertake certain nuclear activities contrary to multiple UNSC (UN Security Council) Resolutions," Britain's ambassador to the International Atomic Energy Agency said in a joint statement delivered to the Vienna meeting.
These include "recent steps to install more advanced centrifuges, continued installation of additional centrifuges at Fordo and Natanz, production of enriched uranium, and construction of the IR-40 reactor at Arak," Susan le Jeune d'Allegeershecque said, according to the text of her remarks.
The statement to a meeting of the 35-nation IAEA board of governors was on behalf of the United States, China, Russia, Britain, France and Germany, known as the P5+1.
The statement also said that the six countries "seek tangible results" from talks with Iran -- which resumed last week in Kazakhstan and which it said were "useful" -- "at an early stage."
These talks saw the P5+1 sweeten an offer made to Iran last year, scaling back some of their demands and offering more relief from sanctions that last year began to hurt the Iranian economy.
Technical experts from both sides are meant to begin thrashing out the details on March 17-18 in Istanbul before chief negotiators return to Almaty on April 5-6.
The IAEA conducts regular inspections of Iran's declared nuclear sites and its quarterly reports routinely outline advances in its atomic programme in spite of UN Security Council resolutions calling for a suspension.
The latest report, issued February 21, said that Iran had begun installing at its Natanz plant more advanced centrifuges to speed up uranium enrichment, a process at the heart of the international community's concerns.
Enriched uranium can be used for peaceful purposes but also, in highly purified form, in a nuclear weapon. Iran denies this is its aim.
The report also repeated that Iran had told the agency that it expected its Arak reactor to start operating in the first quarter of 2014.
This reactor could provide Iran with plutonium, which could also go in a nuclear weapon. Iran denies seeking or ever having sought the bomb.
Tuesday's P5+1 statement also expressed support for the IAEA's separate efforts to persuade Iran to grant access to sites, documents and personnel involved in what the agency suspects may be nuclear weapons research work, mostly in the past but possibly ongoing.
"We commend the Secretariat for its intensive efforts over many months, including nine meetings with Iran over the last year, to clarify unresolved issues in connection with Iran's nuclear program and encourage the Agency to continue doing so," le Jeune said.