Diplomats from the three European countries directly involved in the negotiations to breathe new life in a faltering nuclear deal with Iran have stressed the "urgent" nature of talks.
The eighth round of negotiations aimed at reviving the agreement, which unraveled after the United States withdrew from the accord in 2018 and reimposed tough sanctions on Tehran, opened in Vienna on December 27.
The 2015 agreement limited Iran's nuclear program in return for sanctions relief.
Iran, which claims its nuclear program is for civilian purposes only, reacted to the U.S. withdrawal by gradually ramping up its activities and enriching uranium well beyond the thresholds allowed in the original agreement.
"This negotiation is urgent.... We are clear that we are nearing the point where Iran's escalation of its nuclear program will have completely hollowed out the JCPOA," negotiators from Britain, France, and Germany said in a statement, referring to the deal's official name by its acronym.
"That means we have weeks, not months, to conclude a deal before the JCPOA's core nonproliferation benefits are lost."
Beside negotiators from the three European powers, diplomats from the other two countries that remained party to the deal -- China and Russia -- are also directly taking part in the efforts to restart the accord.
Mikhail Ulyanov, the Russian envoy to the talks, said on December 29 that he had met with his U.S. counterpart, Robert Malley, in Vienna.
"Close consultations and coordination between the Russian and the U.S. delegations in the course of the Vienna talks constitute an important prerequisite for progress towards restoration of the JCPOA," Ulyanov said on Twitter.
The seventh round of talks, the first under new hard-line Iranian President Ebrahim Raisi, ended on December 17 after Tehran added some new demands to a working text, including that U.S. sanctions be lifted.
Tehran has said that it wanted "guarantees" that Washington, which is participating in the Vienna talks indirectly, will return to the accord.
"The most important issue for us is to reach a point where, firstly, Iranian oil can be sold easily and without hindrance," Iranian media quoted Foreign Minister Hossein Amir-Abdollahian as saying in Tehran before negotiations resumed this week.
Russia's envoy to the talks, Mikhail Ulyanov, said on December 28 that the working group was making "indisputable progress."
"Sanctions lifting is being actively discussed in informal settings," he wrote on Twitter.
However, U.S. State Department spokesman Ned Price said Washington thinks it is too soon to say how substantive this progress is, and told reporters the United States has not yet seen sufficient urgency demonstrated by Iran.
Also on December 28, Israeli Prime Minister Naftali Bennett said he is not opposed to a "good" nuclear deal between Iran and world powers, but expressed skepticism that the talks can result in such an outcome.