Israel’s prime minister branded Iran’s new president the "hangman of Tehran" over the weekend and called on world leaders not to restore a nuclear deal with his hardline government.

Ebrahim Raisi was elected with just under 62 per cent of the vote in presidential elections on Thursday, replacing the comparatively moderate and pragmatic President Hassan Rouhani. But his victory was marred by historically low turnout and he is under immense pressure to deliver economic improvements, including via nuclear talks.

He pledged during his election campaign to revive the 2015 nuclear deal with six world powers in a bid to lift punishing US sanctions. Delegates adjourned talks in Vienna on Sunday, with Iranian diplomats saying a deal was "close".

Israel, which is locked in a so-called "shadow war" with the Islamic Republic, says the nuclear deal is insufficient to prevent Tehran from building a bomb.

Mr Bennett’s government branded Mr Raisi a "butcher", alluding to claims that he was complicit in a massacre of thousands of political prisoners in Iranian prisons in 1988.

"Raisi’s election is, I would say, the last chance for the world powers to wake up before returning to the nuclear agreement, and to understand who they are doing business with,” Mr Bennett said in a cabinet meeting on Sunday.

"A regime of brutal hangmen must never be allowed to have weapons of mass destruction,” he added.

Mr Rouhani agreed to curb Iran’s nuclear program, which it insists is purely civilian in nature, in exchange for sanctions relief in 2015.

Donald Trump pulled the US out of the deal three years later and imposed extra sanctions in a bid to force concessions from Iran over its missile program and military activity in the Middle East. Iran responded by resuming nuclear activities banned by the agreement.

A ‘shadow war’ between Iran and Israel intensified in the aftermath of Mr Trump’s withdrawal, with Israel apparently targeting Iranian scientists and other assets linked to what it says is a nuclear weapons program.

Joe Biden’s administration has sought to restore the agreement, but wants Iran to return to full compliance before lifting sanctions. Iran has demanded the US lift sanctions first.

Delegates from Iran, the United Kingdom, France, Germany, Russia and China, the remaining members of the agreement, left Vienna for their respective capitals for consultations on Sunday, amid reports that only "political issues" stood in the way of a deal.  

"We are now closer than ever to an agreement but the distance that exists between us and an agreement remains and bridging it is not an easy job," Iranian delegation chief Abbas Araqchi told Iranian state TV from Vienna. "We will return to Tehran tonight."

Mikhail Ulyanov, the Russian representative to international organisations in Vienna, said the joint committee "decided to make a break to allow participants to consult with the capitals in preparation for what is supposed to be the final round of negotiations."

However, EU officials said that significant political obstacles remained.

Enrique Mora, the European Union official who chaired the final meeting of the sixth round of talks, told reporters that "we are closer to a deal, but we are not still there."

"We have now more clarity on technical documents, all of them quite complex, and that clarity allows us to have also a great idea of what the political problems are."

There is widespread public support for reviving the deal in Iran, which has suffered runaway inflation, stagnant wages and growing unemployment since Mr Trump quit the deal in 2018.

Some diplomats believe Ayatollah Ali Khamenei, Iran’s conservative supreme leader, stalled progress on the agreement to prevent the out-going reformist government from taking credit for a deal.

However, others suggest Iran may seek to rush through an agreement  before Mr Raisi’s inauguration in August to keep his anti-Western credentials intact.

"If the deal is finalised when Rouhani is [still] president, Raisi cannot be criticised by hardline supporters for giving concessions to the West," an Iranian government official who is close to the talks told Reuters news agency. "Also Rouhani, not Raisi, will be blamed for any future problems regarding the deal."