U.S. special envoy for Iran Robert Malley says Iran has added demands unrelated to discussions on its nuclear program during the latest talks in Doha aimed at breaking an impasse in negotiations to revive the 2015 nuclear deal.

'They have, including in Doha, added demands that I think anyone looking at this would be viewed as having nothing to do with the nuclear deal, things that they've wanted in the past,' he said in an interview with National Public Radio.

'The discussion that really needs to take place right now is not so much between us and Iran, although we're prepared to have that. It's between Iran and itself. They need to come to a conclusion about whether they are now prepared to come back into compliance with the deal,' Malley added.

He said that there was a proposal on the table for a timeline by which Iran could come back into compliance with the nuclear deal and Washington could ease sanctions on Tehran.

Two days of indirect negotiations between Iran and the United States ended in Qatar on June 29 after failing to make significant progress.

Under the 2015 nuclear deal, Iran agreed to limits on its controversial nuclear program in exchange for sanctions relief. But the arrangement began to fall apart in 2018 when then- U.S. President Donald Trump pulled out of the deal.

Washington subsequently reimposed crippling sanctions on Tehran, while Tehran gradually backed away from some of the commitments in the deal.

Iran has been engaged for more than a year in negotiations in Vienna with Britain, Germany, France, Russia, and China directly -- and the United States indirectly -- to revive the deal.

Negotiators were reportedly close to a new agreement in March, but the talks abruptly stalled in April, with Tehran and Washington blaming each other for failing to make the necessary political decisions to settle remaining issues.

With reporting by Reuters

Copyright (c) 2018. RFE/RL, Inc. Republished with the permission of Radio Free Europe/Radio Liberty, Washington DC 20036