Iran’s supreme leader Ayatollah Khamenei called the US “stubborn” on Wednesday amid stalled multilateral nuclear talks in Vienna, creating fresh doubt that the faltering negotiations will succeed in finalising a new deal on lifting sanctions against Iran.

The Vienna talks, involving China, Germany, France, Russia and Britain — as well as the US, through a special envoy — aim to revive a 2015 nuclear deal where Iran would limit nuclear research and uranium enrichment and allow nuclear inspectors to return.

Talks are currently on hold amid a government transition in Iran.

Khamenei appeared to describe outgoing President Hassan Rouhani’s eight-year government as naive for its approach in reaching the 2015 agreement as its officials sat before him.

“Others should use your experiences. This experience is a distrust of the West,” Khamenei said, in remarks broadcast by state television.

“In this government, it was shown up that trust in the West does not work.” He added: “Westerners do not help us, they hit wherever they can.”

Talks are due to resume after the swearing in of the new government headed by President-elect Ebrahim Raisi, who won last month's national elections by a significant margin, despite the historically low turnout.

Mr Raisi, who has long been close to Ayatollah Khamenei, has been an outspoken critic of the US.

Iran's most recent demand in the talks is for a clause in any agreement that would ensure the US cannot unilaterally leave a new deal without a UN resolution.

Last month, Iran's parliament, dominated by hardline MPs, tabled legislation that pressed a long-standing demand for sanctions to be lifted by the US before any nuclear concessions could be granted.

Government spokesman Ali Rabiei said that the bill, which also compelled Iran’s government to significantly expand atomic activity and limit nuclear inspections, amounted to “an unorthodox interference in executive affairs” that had complicated the negotiations with world powers in Vienna.

The deadlock comes as the International Atomic Energy Agency said the continuing pause in both negotiations and nuclear inspections had created an “uncomfortable” situation.

“We still have a number of questions, issues that we are trying to clarify with Iran, and we will have to wait and start anew with the new team when they are in office,” IAEA director general Rafael Grossi told AFP in a visit to Brazil on July 20.

The announcement that the process would be resumed only after Mr Raisi takes over “leaves us in a rather uncomfortable situation,” he said.

Mr Raisi has said he wants to revive the deal but Khamenei now seems keen to maintain his historically hardline position.

Mr Raisi is however, determined for Iran to maintain commitments to its missile programs and support for regional militias, including radical Shiite groups in Iraq and Lebanon that have attacked US forces and fired drones at Saudi Arabia, in addition to supporting Houthi militias in Yemen.

“Regional and missile issues are not negotiable,” he said in June.

This support could be a complicating factor when talks go ahead. On Tuesday, the spokesman for Kataib Hezbollah, a militia group in Iraq backed by Iran and accused of firing drones into Saudi Arabia and attacking US forces, said it would attack “any country in the region” where US troops are based.