US Secretary of State John Kerry and foreign ministers of five other world powers joined talks on Irans contested nuclear programme on Saturday with the two sides edging towards a breakthrough to ease a dangerous decade-old standoff.
The Chinese,Russian,French,British and German foreign ministers Wang Yi,Sergei Lavrov,Laurent Fabius,William Hague and Guido Westerwelle all pulled up their sleeves to try to seal an interim deal under which Iran would cap its nuclear activity in exchange for relief from sanctions.
Hague and Westerwelle cautioned that a preliminary accord to turn the page on years of confrontation with the Islamic Republic was not yet guaranteed and that there was much work to do to bridge remaining differences.
Diplomats earlier said a formidable sticking point in the intense negotiations may have been overcome with compromise language that does not explicitly recognise Irans claim to a right to enrich uranium but acknowledges all countries right to their own civilian nuclear energy.
But Russian Deputy Foreign Minister Sergei Ryabkov said Irans demand to continue construction of a heavy-water reactor near Arak that could yield plutonium an alternative bomb material remained a tough outstanding issue.