Six world powers and Iran are getting close to a first-stage agreement to curb the Islamic Republic's nuclear programme, a senior US official has said.
The official told reporters in Washington on Friday that it was "quite possible" a deal could be reached when the parties meet on November 21-22 in Geneva, according to the Reuters news agency, which did not name the official.
"I don't know if we will reach an agreement. I think it is quite possible that we can, but there are still tough issues to negotiate," said the official.
The official added that Catherine Ashton, the EU foreign policy chief, and Javad Zarif, the Iranian foreign minister, were to meet on November 20 in Geneva and a wider group - including Security Council permanent members Britain, China, France, Russia, the United States and Germany - would meet Iranian officials there on the following two days.
The UN nuclear agency said this week the Iranian government had slowed its pace of uranium enrichment ahead of a new round of talks.
No new components
In a report on Thursday, the International Atomic Energy Agency said that no major new components had been installed at the unfinished Arak reactor, a heavy water facility that was due to come online next year.
Arak, which could produce plutonium when running, was a major sticking point in talks between Iran and the powers in Geneva last week.
The IAEA report stated that Iran had installed only four first-generation centrifuges at the Natanz plant- machines used to refine uranium - but not all of the installed centrifuges were operating.
The quarterly report was the first that included developments since Hassan Rouhani took office as president early in August, prompting a diplomatic opening between Iran and the six nations.
It also showed that Iran's stockpile of higher-grade enriched uranium had risen by about 5 percent to 196kg since August, largely due to a temporary halt in converting the material into reactor fuel.
But the amount of uranium gas enriched to a fissile concentration of 20 percent still remained below the roughly 250kg needed for a bomb if processed further - an amount that Israel has indicated is a "red line" that could trigger military action against Iran.
The last round of talks in Geneva ended without a breakthrough, with France saying a first-stage agreement with Tehran would do little to halt its nuclear programme.
Iran insists its nuclear programme is intended for civilian use but Western nations, suspecting it is bent on developing a nuclear bomb, have imposed crippling sanctions.
Barack Obama, the US president, has urged members of Congress not to impose new sanctions against Iran.
Obama said that if Iran can't deliver on future promises and commitments, "the sanctions can be ramped back up".