GENEVA — Secretary of State John Kerry will travel to Geneva to give a boost to stalled nuclear talks with Iran, the State Department said on Friday, raising hopes that a historic deal could be reached over the weekend.
Kerry decided to join the negotiations after diplomats reported progress in narrowing differences with Iran over a proposal that would scale back key parts of its nuclear program, Western officials said. His visit would be the second time in as many weeks that Kerry has used personal diplomacy to try to conclude a deal.
Under the proposed six-month deal that six major powers are negotiating in Geneva, Iran would eliminate its current stock of uranium enriched to 20 percent by diluting it or turning it into fuel rods or oxide powder, forms that are unusable for weapons, senior Western officials said Friday.
Iran would be allowed to continue to enrich uranium at much lower levels, to 3.5 percent, the officials said, but would also agree to cap its current stockpile of such uranium, by eliminating, diluting or transforming into fuel as much 3.5 percent uranium as it produces over the six months.
The officials spoke about the deal on the condition of anonymity, because the negotiations had not been completed.
‘‘Secretary Kerry will travel to Geneva later today with the goal of continuing to help narrow the differences and move closer to an agreement,’’ State Department spokeswoman Jen Psaki said in a statement.
That announcement came hours after Russian Foreign Minister Sergei Lavrov arrived in Geneva to join the negotiations, which have been underway since Wednesday. Diplomats from Iran and six major powers had reportedly made faltering progress in their attempts to resolve a number of sticking points, including Iran’s insistence on international recognition of its ‘‘right’’ to enrich uranium.
Britain’s foreign secretary, William Hague, announced that he would also join the talks Saturday.
The rationale for the proposed deal, the officials said, is to satisfy Iran’s refusal to suspend all enrichment — a concession that its negotiators could not sell domestically, even for six months. But in exchange, Iran would agree to cap its stockpile, while eliminating its current supply of the more highly enriched uranium, which is much closer to bomb grade and has caused anxiety among Western nations, Israel and the Arab gulf nations, including Saudi Arabia.
The plan is intended to essentially freeze Iran’s nuclear expansion while diplomats attempt to negotiate permanent limits on Iran’s ability to produce nuclear weapons. Iran insists that its nuclear facilities are intended only for energy production.
The news of Kerry’s impending arrival capped a day in which prospects for a deal appeared to brighten appreciably. Iranian officials, who had given generally gloomy assessments of the talks earlier, were visibly upbeat as the meetings dragged on. Iranian media reported that progress had been made on one of the main points of contention: Iran’s insistence that global powers acknowledge its ‘‘right’’ to make enriched uranium. Western diplomats declined to comment on the report.
‘‘If you’re asking about the amount of work that has been done, we have moved forward up to 90 percent,’’ Iranian Foreign Minister Mohammad Javad Zarif told Iranian journalists during a break in the talks, according to Iran’s semiofficial Press TV news service. Zarif said only ‘‘one or two issues’’ remained to be resolved.
On the key issue of uranium enrichment, Zarif said making the nuclear fuel for Iranian power plants was ‘‘a right that Iran will not withdraw from.’’
US diplomats have described efforts to find language that would satisfy Iran without implying legal recognition of a right to enrichment.
The Geneva meeting is the third round of international talks on Iran’s nuclear program since moderate cleric Hassan Rouhani assumed the presidency in August. The sides fell just short of reaching an agreement two weeks ago, when Kerry and his counterparts from Europe and Russia flew to Geneva at the eleventh hour to try to close the deal.