Iranian Deputy Foreign Minister and top nuclear negotiator Abbas Araqchi (L, Front) and Enrique Mora, deputy secretary-general and political director of the European External Action Service, leave the venue of a meeting of the Joint Commission on the Joint Comprehensive Plan of Action (JCPOA) in Vienna, Austria, on June 2, 2021. (Xinhua/Guo Chen)

The EU diplomat also noted that this round of talks has taken place "against important political developments," citing the recent meeting of EU High Representative for Foreign Affairs and Security Policy Josep Borrell and the U.S. officials in the EU-U.S. summit and Borrell's meeting with Iranian Foreign Minister Mohammad Javad Zarif.

"Welcomed progress made over last weeks, but difficult decisions remain. It is important to seize the political opportunity, and for all to be flexible. In view of today's Presidential elections, I called for continued commitment by Iran," Borrell tweeted Friday after meeting with Zarif.

Seyyed Abbas Araghchi, Iran's deputy foreign minister and top nuclear negotiator, told reporters before the meeting that documents for an agreement on the revival of the 2015 nuclear deal are almost ready, the official IRNA news agency reported.

"We are closer to an agreement ever than before, but bridging the gaps ... requires decisions by the parties," he said, adding that some issues still need to be resolved.

The U.S. administration under former President Donald Trump withdrew from the JCPOA in May 2018 and unilaterally reimposed sanctions on Iran. In response to the U.S. moves, Iran gradually stopped implementing parts of its JCPOA commitments from May 2019.

The JCPOA Joint Commission began to meet in offline format on April 6 in Vienna to continue previous discussions in view of a possible return of the United States to the JCPOA and on how to ensure the full and effective implementation of the JCPOA.