The European Union's Josep Borrell says the deal is at "95 percent but the last five percent is critical," as EU coordinator for the nuclear talks, Enrique Mora, travels to Tehran to close gaps in the negotiations.
Top EU diplomat Josep Borrell has said Iran and world powers were "very close" to agreement on reviving their 2015 nuclear deal, which would curb Tehran's nuclear programme in exchange for lifting tough sanctions.
"Now we are very close to an agreement and I hope it will be possible," the European Union's Borrell said in an address to the Doha Forum international conference on Saturday.
"We are at 95 percent but the last five percent is critical," according to Borrell, who said the last major obstacle was removed when Russia ended its opposition to a deal earlier this month.
"We want to prevent the nuclear programme from advancing," Borrell said. "I will be very disappointed if it does not happen."
Then-US President Donald Trump abandoned the pact in 2018, prompting Tehran to start violating its nuclear limits about a year later, and 11 months of on-and-off talks to revive it paused in Vienna earlier this month after Russia presented a new obstacle.
Russia later said it had received written guarantees that it would be able to carry out its work as a party to the deal, suggesting Moscow could allow it to be resuscitated.
There are several difficult issues pending. The Trump administration designated Iran's elite Islamic Revolutionary Guard Corps (IRGC) as US foreign terrorist organisation (FTO).
Iranian Foreign Minister Hossein Amirabdollahian said on Saturday that the lifting of US sanctions on the IRGC was among Iran's top demands in talks to revive a 2015 nuclear accord.
"Certainly the issue of (lifting sanctions against) the Guards is part of the talks," Amirabdollahian told state TV, adding that Iran would not cross its "red lines."
Tehran has also been seeking guarantees that the United States will not unilaterally withdraw from any agreement. The extent to which sanctions would be rolled back is another sensitive subject.