The ball is now in Washington's court, the Islamic republic said.

Foreign Minister Hossein Amir-Abdollahian said on Twitter that negotiations in Vienna were "proceeding with seriousness" and the removal of sanctions was a "fundamental priority".

The talks resumed on Monday after Iran paused them in June following the election of ultraconservative President Ebrahim Raisi.

European diplomats had warned on Tuesday that "we don't have the luxury to spend time on niceties" and they would assess the "seriousness" of Iran's position in the next 48 hours.

In his tweet, the foreign minister said experts' talks were continuing and that he was in daily contact with his deputy and lead negotiator, Ali Bagheri.

"Good deal within reach if the West shows goodwill. We seek rational, sober and result-oriented dialogue," said Amir-Abdollahian.

Bagheri told reporters in Vienna on Thursday that Iran has submitted draft proposals on the lifting of sanctions and Tehran's nuclear commitments.

"We have given them two proposed drafts... Of course they must consult the texts we gave them," he said.

- 'Ball in US court' -

The 2015 accord offered Iran a lifting of economic sanctions in return for strict curbs on its nuclear activities.

The goal of the Joint Comprehensive Plan of Action, or JCPOA, is to make it practically impossible for Iran to build an atomic bomb, while allowing it to pursue a civilian nuclear programme.

But the deal started to unravel in 2018 when then US president Donald Trump pulled out and began imposing sanctions on the Islamic republic.

In turn, Iran, which denies it wants to acquire a nuclear arsenal, has gradually abandoned its commitments since 2019.

Iran's Fars news agency said lead negotiator Bagheri would meet Thursday with Rafael Grossi, head of the UN's International Atomic Energy Agency (IAEA).

In an interview with the Middle East Eye website, Bagheri said Tehran did not feel under pressure.

"The issue of the negotiations now is not related to Iran. It is related to the United States," he said.

"Therefore, now the ball is in the court of the Americans. The Americans must remove the sanctions."

The remaining parties to the 2015 agreement -- Britain, China, France, Germany and Russia -- are participating directly in the Vienna talks.

At Iran's insistence, the United States is doing so only indirectly.

Israeli Prime Minister Naftali Bennet on Thursday called for an "immediate cessation" of the Vienna talks, accusing Iran of "nuclear blackmail".

Grossi on Wednesday reported "no progress" in talks he held in Tehran last week on disputes over the monitoring of Iran's atomic programme.

He said Iran has begun enriching uranium to 20 percent level -- over the terms agreed in the 2015 deal -- at the Fordo underground facility using advanced centrifuges.