Iran's chief nuclear negotiator Ali Bagheri Kani leaves after a meeting of the Joint Comprehensive Plan of Action (JCPOA) in Vienna, Austria, 29 November 2021; Credit: Reuters / Lisi Niesner / File Photo

VIENNA (Reuters) - Iran accused Western parties to its 2015 nuclear deal on Tuesday of "persisting in their blame game", a day after European diplomats warned the pact would soon become defunct if efforts to revive it fail.

In a pessimistic assessment of talks between Iran and major powers in Vienna, diplomats from the United Kingdom, France and Germany warned on Monday that "time is running out" to rescue the pact, which they said would very soon become "an empty shell" without progress in negotiations.

Iran's top nuclear negotiator, Ali Bagheri Kani, responded on Twitter by saying: "Some actors persist in their blame game habit, instead of real diplomacy. We proposed our ideas early, and worked constructively and flexibly to narrow gaps".

Referring to the United States and its withdrawal from the nuclear pact in 2018, Mr Kani wrote: "Diplomacy is a two-way street. If there's real will to remedy the culprit's wrongdoing, the way for a quick, good deal will be paved".

However, US Secretary of State Antony Blinken said on Tuesday that Washington continues to pursue diplomacy with Iran because "it remains, at this moment, the best option", but added that it was "actively engaging with allies and partners on alternatives".

The stakes are high. Failure in the negotiations would carry the risk of a new regional war, with Israel pushing for a tough policy if diplomacy fails to rein in Iran’s nuclear work.

Indirect talks between arch-foes Iran and the United States started in April, but stopped in June after the election of hardline cleric Ebrahim Raisi, whose negotiating team has returned to Vienna after five months with an uncompromising stance.

In 2019, Iran started breaching nuclear restrictions under the pact in response to the US withdrawal and decision to reimpose harsh sanctions which have devastated Iran’s economy.

"Who violated the deal? Americans. Who should compensate for that and be flexible? Americans of course", said a senior Iranian official.

Iran's clerical rulers believe that a tough approach, spearheaded by their strongly anti-Western Supreme Leader Ayatollah Ali Khamenei, can force Washington to accept Tehran’s "maximalist demands", analysts and diplomats said.

"But it could backfire. This is a very dangerous and sensitive issue. Failure of diplomacy will have consequences for everyone", said a diplomat in the Middle East on condition of anonymity.

Significant Gaps

During the seventh round of talks, which began on 29 November 2021, Iran abandoned any compromises it had made in the previous six, and demanded more, a senior US official has said.

With significant gaps remaining between Iran and the United States on some key issues (such as the speed and scope of lifting sanctions and how and when Iran will reverse its nuclear steps) chances of an agreement seem remote.

Iran insists on immediate removal of all sanctions in a verifiable process. Washington has said it would remove curbs "inconsistent" with the nuclear pact if Iran resumed compliance, implying it would leave in place others such as those imposed under terrorism or human rights measures.

Iran also seeks guarantees that "no US administration" will renege on the pact again. But President Joe Biden cannot promise this because the nuclear deal is a non-binding political understanding, not a legally binding treaty.

"How can we trust Americans again? What if they ditch the deal again? Therefore the party that violated the deal should provide guarantees that it will never happen again", said the Iranian official. "This is their problem not ours to solve ... They can find a solution and give us guarantees".

Dramatically upping the ante, Iran has also limited access given to UN nuclear watchdog inspectors under the nuclear deal, restricting their visits to declared nuclear sites only.

Though essential to reinstate the nuclear pact, the International Atomic Energy Agency (IAEA) said last month it had not had access to re-install surveillance cameras at the TESA Karaj centrifuge-parts workshop in Iran, which was hit by apparent sabotage in June in which one of four cameras of the agency there was destroyed.

"Our talks with the IAEA about the Karaj complex still continue", Iran's top nuclear official Mohammad Eslami said, according to Iranian media.