The same day, Mikhail Ulyanov, Russia's envoy to the talks, said that indisputable progress has been in made in Vienna, adding that sanctions lifting is being seriously discussed in informal settings. 

Ulyanov is participating in the eighth round of talks on the Iran nuclear deal, which resumed on Monday.

In previous negotiations, negotiators from Britain, France, and Germany were pessimistic about the possibility of reviving the JCPOA.