Apart from Abbas Araqchi, Majid Takht-e Ravanchi and Wendy Sherman, the deputy foreign ministers of Iran and the US who attended the meeting, head of the Atomic Energy Organization of Iran Ali-Akbar Salehi and US Secretary of Energy Ernest Moniz, as well as Hossein Fereidoun, a special advisor to President Hassan Rouhani were present at the talks, IRNA reports.

Earlier in the day, Salehi and Moniz had discussed the remaining technical differences.

But Reuters has another story, according to this agency, Iran and major powers remain "pretty far" from a nuclear deal, a European diplomat in crunch talks in Switzerland said Thursday.

"I think we are pretty far from a deal," the negotiator said on condition of anonymity. "I really don't believe that we are going to get a (framework) deal on Friday night."

US Secretary of State John Kerry, his Iranian counterpart and negotiators from Russia, China, Britain, France, Germany and the EU are racing to meet a March 31 deadline for the outlines of a deal.

Such an accord, due to be finalized by July. The mooted accord is however highly complex and would involve Iran scaling down its nuclear activities in exchange for staggered relief from sanctions.

In Tehran Foreign Ministry Spokeswoman Marzieh Afkham said Thursday that reaching a nuclear agreement between Iran and the six world powers – known as the P5+1 – rests upon the political resolve of negotiating parties.

In an interview with Lebanon's al-Ahd news service, Afkham said that nuclear talks in the Swiss town of Lausanne have entered a critical stage.

A good deal for Iran is one that will lead to complete lifting of arbitrary and illegal sanctions and accepting Iran's right to peaceful nuclear technology as a signatory to the Non-Proliferation Treaty, she added.