The signatories to the 2015 nuclear deal, officially known as the JCPOA, meet in Vienna on Tuesday. 

The meeting falls within the sessions of the JCPOA Joint Commission. The meeting is being held while the U.S. is isolated due to its illegal moves to extend arms embargo against Iran or return the UN sanctions against the country. 

Deputy Foreign Minister for Political Affairs Abbas Araghchi, who acts as Foreign Minister Zarif's right-hand man on the JCPOA, is representing Iran at the meeting.

Britain, France, Germany, China, Russia and the European Union - the remaining parties to the JCPOA - as well as almost all the non-permanent members of the UN Security Council are struggling to save the landmark accord with Iran.

In a boost to Tuesday's talks, the Atomic Energy Organization of Iran (AEOI) last week agreed for inspectors of the UN nuclear watchdog to visit two sites which allegedly hosted nuclear activity in the early 2000s.

Iran agreed to inspection of the two places after International Atomic Energy Agency (IAEA) director Rafael Grossi made a trip to Tehran last week.

Mikhail Ulyanov, Russia's ambassador to international organizations in Vienna, said on Monday on Twitter that "nuclear deal participants have a lot of topics to discuss".

According to AFP, the meeting is chaired by EU senior official Helga-Maria Schmid with deputy foreign ministers or political directors from Britain, China, France, Germany, Iran and Russia attending.

Mark Fitzpatrick, an associate fellow of the International Institute for Strategic Studies (IISS), said last week's agreement on access kept "Iran generally in line with the rest of the world, against an isolated United States".

PA/PA