Bagheri Kani and the heads of delegations of three European countries returned to their capitals on Friday for further consultations.
The Iranian top negotiator returned to Vienna today to resume talks with the P4+1 after he held several consultations in his two-day stay in Tehran with senior officials on technical and expert issues.
Official meetings of different working groups will reconvene later today in Vienna.
Iran and the P4+1 are negotiating for a possible return of the US to the 2015 nuclear deal, formally known as the Joint Comprehensive Plan of Action or simply the JCPOA.
9416**9417
Follow us on Twitter @IrnaEnglish