Geneva: Iranian and Western officials poured cold water on Saturday on hopes that a landmark nuclear deal was all but sewn up after world power foreign ministers flew in to join talks with Tehran in Geneva.
"We have now entered a very difficult stage," Iranian Foreign Minister Mohammad Javad Zarif told state television from the third round of talks in six weeks in Switzerland.
The talks, held in the plush suites of a Geneva hotel, are aimed at securing a freeze on parts of Iran`s nuclear programme in order to ease fears that it will develop atomic weapons, in return for modest sanctions relief.
"They remain very difficult negotiations. I think it is important to stress that we are not here because things are necessarily finished," British Foreign Secretary William Hague said.
"It`s not a done deal," said his German counterpart Guido Westerwelle. "We think there`s a realistic chance but there is still a lot of work to do."
The arrival of foreign ministers including US Secretary of State John Kerry today raised hopes, after three days of intense negotiations among political directors, that a breakthrough was in sight.
Kerry decided to return to Switzerland "in light of the progress being made" and "with the hope that an agreement will be reached," the State Department said.
China`s Foreign Ministry said the talks were "entering their final phase", while Russia`s top diplomat Sergei Lavrov said that "for the first time in many years" there was a "real opportunity".
Just two weeks ago, the ministers had jetted in seeking to sign on the dotted line, only to fail as cracks appeared among the powers -- fissures that officials say are now repaired.
"It`s the homestretch but preceding negotiations have taught us prudence," a French diplomat said.
Since being elected in June, Iranian President Hassan Rouhani has raised big hopes that after a decade of rising tensions over Tehran`s nuclear programme a solution might be within reach.
The risks posed by failure are high: Tehran could resume the expansion of its nuclear activities, leading to more painful sanctions and even Israeli and possibly US military action.
The Geneva talks are the third round since Rouhani took office with the permanent five UN Security Council members -- the United States, Russia, China, Britain and France -- plus Germany, known as the P5+1.
Iran says its nuclear programme is peaceful but many in the international community suspect it is aimed at acquiring atomic weapons.