Iran’s lead negotiator says Tehran will not accept anything less than the nuclear agreement it signed with world powers in 2015, stressing that the issue will remain Tehran’s red line at the ongoing talks in Vienna.

"We will definitely agree to nothing less than that agreement and this will certainly be a red line for the Islamic Republic of Iran,"  Ali Bagheri Kani told Press TV on Saturday.

“We have a basic red line, which is backed up by logic,” he said, adding, “We have an agreement that was finalized by Iran and the P5+1 in 2015. The US withdrew from it a few years later and now it wants to rejoin that deal. So, this agreement is a shared basis between the two sides."

He said several points of difference have remained unresolved in the draft text that was the outcome of the six rounds of talks held between April and June, adding that they required decision-making at the highest levels.

The lead negotiator explained that some of Iran's proposals were accepted by the opposing side, while others were not.

As for the remaining issues of contention, they “will form the core of serious negotiations at the level of senior negotiators of Iran and the P4+1."

During the seventh round of the Vienna talks, which began on November 29, Iran presented two draft texts which address, the removal of US sanctions and Iran’s nuclear commitments under the JCPOA. Tehran also said it was preparing a third draft text on the verification of the sanctions removal.

US and EU diplomats have voiced strong pessimism about the prospects of the talks, claiming Iran was not serious.

The US, in the meantime, has said it will not remove all the sanctions that they slapped on Iran after the US withdrawal and has also declined to provide guarantees that it will not leave the JCPOA again once it is accepted back into the deal. 

The US announced new sanctions on Iran on Tuesday, despite the resumption of the talks.

Read more: Reframing Vienna: What about Iran's side of the story?

Asked about the prospects of the negotiations under the US government’s new approach, Bagheri Kani refused to make any “prejudgments,” saying Iran is still waiting to see what the Americans will do in practice.

“In the new round of talks, we will make no prejudgments about the conduct of the Americans. We are waiting to see their new approach in this round and will then make judgments accordingly,” he said.