Iran said on Thursday it had handed European powers two draft proposals to try to revive a 2015 nuclear deal, as the Europeans and US said time is of the essence.

Lead negotiator Ali Bagheri told Iranian state television the proposals concern two main issues facing the pact: the lifting of sanctions and Iran's nuclear commitments.

They were submitted on Wednesday, the third day of talks in Vienna to revive the agreement known as the Joint Comprehensive Plan of Action (JCPOA), which offered the Islamic republic a lifting of some sanctions stifling its economy in return for strict curbs on its nuclear activities.

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

"The first document sums up the Islamic republic's point of view concerning the lifting of sanctions, while the second is about Iran's nuclear actions," Bagheri told IRIB TV.

"Now the other side must examine these documents and prepare itself to hold negotiations with Iran based on these documents," said Bagheri.

Later Thursday, US Secretary of State Antony Blinken said "the hour is getting very late, (but) it is not too late for Iran to reverse course."

European negotiators on Tuesday said they will assess the "seriousness" of the Iranian position over the next few days to decide whether to continue the talks.

European diplomats warned there was no time for "niceties" and said the "next 48 hours will be very important".

Diplomats from Britain, China, France, Germany and Russia are attending the talk alongside Iran.

US President Joe Biden's administration, eager to get back into the deal, is indirectly involved in the Vienna discussion.

The deal started to unravel in 2018 when then US president Donald Trump pulled out and began imposing new sanctions on Iran.

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

Biden's administration says it will only negotiate measures taken by Trump over the nuclear programme, such as a unilateral ban on oil sales -- not steps imposed on other concerns such as human rights.

But Iran wants a lifting of all US sanctions imposed after Trump's withdrawal.

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

Iran's chief nuclear negotiator Ali Bagheri arrives at the Coburg Palais, the Vienna venue for talks aimed at reviving the 2015 deal with world powers Iran's chief nuclear negotiator Ali Bagheri arrives at the Coburg Palais, the Vienna venue for talks aimed at reviving the 2015 deal with world powers Photo: AFP / VLADIMIR SIMICEK

Bagheri, echoing Foreign Minister Hossein Amir-Abdollahian, said Iran was in Vienna to resume talks but said it's up to the West.

"We have told the other side that we are in Vienna to pursue the talks... If they are ready to pursue the talks, we agree to pursue them," he told journalists in Vienna.

He said a timetable for the resumption of negotiations would be set up on Thursday.

Earlier, Iran's foreign minister tweeted that an agreement to revive the nuclear deal with world powers was "within reach".

The negotiations in Vienna are "proceeding with seriousness" and the removal of sanctions was a "fundamental priority", said Amir-Abdollahian.

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

And in an interview with the Middle East Eye website published on Thursday, 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."

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

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.

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