Diplomats from Iran and world powers have started the eighth round of talks in Vienna to revive the 2015 nuclear agreement (JCPOA).

The new round of the JCPOA Joint Commission is underway behind closed doors at the Palais Coburg on Monday evening. The commission is comprised of diplomats from Russia, China, Germany, Britain, France and Iran plus a European Union representative, the signatories to the agreement, which the United States left in 2018.

Minutes before leaving for the hotel, Iran’s top negotiator Ali Bagheri-Kani expressed hope about the results of the talks, saying that he is optimistic about this leg of the negotiations.

Before the official start of talks, Bagheri-Kani had meetings with the heads of Russian and Chinese delegations as well as one with EU coordinator Enrique Mora. Other participants also held meetings in various smaller formats.

Bagheri-Kani also met with the French representative after about a week of harsh rhetoric by Iranian media about France sabotaging the talks.

Iran's foreign minister had earlier criticized Paris for taking "unconstructive" stances in the talks.

"Today all parties have agreed to come back to activate the eighth round of negotiations even in Christmas and New Year's holiday. This in itself fully shows a greater sense of urgency on the part of all parties concerned," China's top envoy Wang Qun told reporters before the talks start.

The parties will discuss US sanctions-lifting and Iran's atomic commitments in parallel despite comments by Tehran and Beijing suggesting sanctions would be the focus, the talks' coordinator said.

"We are working on both tracks in parallel ... We are not working on one side and forgetting or neglecting the other. On the contrary, both tracks are mutually reinforcing," European Union envoy Enrique Mora, the talks' coordinator, told a news conference.

Russian envoy Mikhail Ulyanov twitted, “We discussed possible ways ahead at presumably final round of negotiations on restoration of the JCPOA” after a meeting with the EU coordinator.

Ulyanov also said, "This morning the delegations of Russia, China and Iran met to compare notes” before the official start of the 8th round of the plenary meeting.

Iranian and US officials don’t meet face-to-face, so other parties must shuttle between the two sides.

The seventh round of talks, the first under the administration of President Ebrahim Raisi, wrapped up 10 days ago with some new Iranian demands added to a working draft. The progress seemed to be too slow while the Western powers said negotiators had "weeks not months" left before the 2015 deal becomes meaningless.

Formally, the three European states, known as the ‘E3,’ have called on the US to withdraw sanctions incompatible with the JCPOA, and they have urged Iran to return its nuclear program, expanded since 2019, to JCPOA limits.