The Director-General of the IAEA said on Wednesday that talks on the nuclear deal have stumbled on non-nuclear issues.

Speaking at a nuclear panel at the Davos Economic Forum in Switzerland, Rafael Grossi said that the nuclear aspects of the talks to revive the JCPOA are "pretty much finalized", adding that "there are doubts."

"This has been a long process — ongoing for more than a year — which at the moment seems to be going through a great deal of difficulty because of things that have perhaps not much to do with nuclear matters," he explained. 

The advisor to the Iranian delegation in the talks to revive the nuclear deal in Vienna, Mohammad Marandi, said on May 14 that there are many reasons that prevented the nuclear deal from being signed so far, noting that the US terror list is not the main issue.

Marandi told Sputnik that after EU coordinator Enrique Mora's visit to Tehran, we're waiting to see if the Americans are willing to show the required flexibility to sign the deal or not.

The advisor said that Europe and the US are currently facing an economic crisis and an energy crisis, and are in desperate need for a deal with Iran. He also noted that "we'll see whether or not the current US administration's motivations are enough to sign the deal and stand against its opponents in Washington."