A senior nuclear negotiator described discussions with delegates from the European Union and the US in Vienna as "useful".
"We had very useful discussions concerning the bill which is passing (US) congress," Fars news agency quoted Abbas Araqchi as telling state television on Friday, in reference to the bill recently approved by the US Senate foreign relations panel calling for congressional review and approval of a prospective nuclear agreement with Iran.
A new round of negotiations with the major powers to start writing the text of a final nuclear agreement began on Wednesday in the Austrian capital with a meeting between Iranian negotiators and European Union political director Helga Schmid.
Asked about the main focus of this round of talks, the deputy foreign minister said, "Our priority is discussion about sanctions to make their aspects and details clear and start writing down what we agree in this relation."
"(There exist) various questions regarding the removal of sanctions, which we are discussing. The results should be written down," he said, adding that "any progress" made will be made public.
The removal of multilayered sanctions which Iran has consistently dubbed as "unlawful and unjust" has been Tehran's main demand throughout the negotiations. However, recent developments, particularly the passage of the review bill by the Senate panel, seem to have cast some doubt over the US policymakers' overall intentions regarding the whole negotiations.
The negotiating team also met the US delegation headed by Under Secretary of State Wendy Sherman on Thursday.
Iran and its international negotiating partners, which have been in talks to reach a settlement to a 12-year dispute over Tehran's nuclear program, concluded an outline agreement on April 2 and are trying now to finalize the details of the comprehensive deal by a self-imposed end-June deadline.
Under the final pact, Iran would accept some restrictions on its nuclear program for a specified period of time in exchange for sanctions relief.
On the process of drafting the final deal, Araqchi said, "We are at the start of the work to write the text and this process is expected to be slow until we work out" where to start and how to proceed.
"However, overall, the effort to write is going well."
Regarding the differences with the American side over the timing of lifting sanctions, he said, "Both the American and European sides provided very good clarification regarding the issue."
Iran insists that sanctions should be lifted as soon as any final deal takes effect, while the US wants sanctions to be phased out gradually.
The three-day Vienna talks ended on Friday with a meeting between representatives of Iran and the P5+1 (the five permanent members of the United Nations Security Council plus Germany).
