Iran and the P5+1 group representatives Wednesday started the second round of talks on drafting a final agreement on Tehran's nuclear programme in the Austrian capital.

Iranian Deputy Foreign Minister for Legal and International Affairs Abbas Araqchi, who is leading the Iranian delegation in the talks, began the second meeting with the EU political director, Helga Schmid.

The second round of the talks between representatives of Iran and the P5+1 - the United States, Russia, China, France, Britain, and Germany – are set to last three days with the aim of drafting a nuclear accord.

The two groups met for the first round of negotiations earlier in the day as part of a meeting also attended by Iran Foreign Ministry Political Affairs Director General Hamid Baeidinejad, as well as Iranian Deputy Foreign Minister for European and American Affairs Majid Takht-e Ravanchi and other experts.

Representatives of the P5+1 group of countries, including US Under Secretary of State for Political Affairs Wendy Sherman, are expected to join the talks on Friday.

Araqchi said in the second round Iran will demand that the US representatives in the negotiations provide the Iranian team with "clear, precise information" on "the details related to the lifting of the sanctions".

Iran will also ask US to explain the approval of a bill by the Senate Foreign Relations Committee that would allow Congress to review a possible final nuclear agreement with Iran.

The legislation was voted on in the US Senate committee in a 19-0 vote on April 14.