Iran’s supreme leader on Wednesday dismissed initial offers at talks in Vienna to save Tehran’s tattered nuclear deal as “not worth looking at,” as Tehran seeks to pressure world powers after an attack on the country’s main nuclear enrichment site.

The comments by Ayatollah Ali Khamenei, who has a final say on all matters of state, came after a day that saw Iran’s president similarly ratchet up pressure over the accord. European powers, meanwhile, warned Tehran its actions were “particularly regrettable” and “dangerous.”

The talks have already been thrown into disarray by a weekend attack on Iran’s main Natanz nuclear enrichment site that Tehran says was carried out by Israel – who have made no official comment on the matter.

Tehran retaliated by announcing it would enrich uranium up to 60 per cent – higher than it ever has before but still lower than weapons-grade levels of 90 per cent.

‘The offers they provide are usually arrogant and humiliating [and] are not worth looking at,” the 81-year-old Mr Khamenei said in an address marking the first day of Ramadan in Iran.

He also criticised the US and warned time could be running out.

“The talks shouldn’t become talks of attrition,” Mr Khamenei said. “They shouldn’t be in a way that parties drag on and prolong the talks. This is harmful to the country.”

Speaking to his Cabinet, an impassioned Iranian President Hassan Rouhani said the first-generation IR-1 centrifuges that were damaged in Sunday’s attack would be replaced by advanced IR-6 centrifuges that enrich uranium much faster.

“You wanted to make our hands empty during the talks but our hands are full,” Mr Rouhani said.

“Sixty per cent enrichment is an answer to your evilness. … We cut off both of your hands, one with IR-6 centrifuges and another one with 60 per cent,” he said

Rouhani also accused Israel of being behind the Natanz attack and threatened to retaliate.

In Jerusalem at a Memorial Day commemoration, Israeli Prime Minister Benjamin Netanyahu appeared to reference Iran but spoke indirectly.

“We must never remain apathetic to the threats of war and extermination of those who seek to eliminate us,” he said.

Israel has not claimed the attack, though it rarely does in its ongoing shadow war against Tehran.

The talks in Vienna aim to find a way for the United States to re-enter Tehran’s nuclear agreement with world powers and have Iran comply again with its limits.

The accord, which former President Donald Trump unilaterally withdrew the US from in 2018, prevented Iran from stockpiling enough high-enriched uranium to be able to pursue a nuclear weapon in exchange for the lifting of economic sanctions.