Russia's deputy foreign minister, Sergei Ryabkov, said Tuesday he was "reasonably optimistic" world powers can reach a nuclear deal with Iran by a November 24 deadline, despite big gaps remaining.
"We are not working on plan B, that's for sure," he told reporters in Muscat, though he did not rule out an extension.
"If by whatever reason, by whatever development, we are not there, I think we will have time on the evening of the 23rd to develop an alternative."
Ryabkov, Russia's chief negotiator in the talks, made a brief unscheduled appearance at the media centre and spoke candidly of the problems left to be resolved in the next two weeks.
Asked why the talks appeared to be in stalemate, Ryabkov cited the "inability of parties to build bridges over still deep gaps on issues like enrichment, like sanctions."
"The glass is not half empty. We are reasonably optimistic but not to an extent that we are sure that this agreement can be achieved. It is really a unique and never tried before effort," he said.
"There is a chance, there is no reason to be negative or pessimistic. We are confident we will be able to achieve this goal," Ryabkov said.
He urged parties in the talks to "not kill the chances" of a deal by November 24, adding that all countries knew that "in the absence of creativity and responsibility" the talks could fail.