"Iran has submitted a written response to the draft text of a Vienna agreement and has announced that an agreement will be concluded if the United States reacts with realism and flexibility," the official IRNA news agency reported.

The possibility of a deal which might lead to the lifting of US sanctions on Iran's oil output of 2.5 million barrels per day has already helped trigger a fall in prices on world markets, with US oil futures dropping nearly three percent to finish below $90 a barrel.

IRNA had said Friday that Iran might accept the "final" text drawn up by the European Union to save the deal, which aimed to curb Iran's nuclear programme in return for sanctions relief.

The deal has been moribund since the 2018 withdrawal of the United States under then president Donald Trump whose administration reimposed crippling sanctions.

The major powers have been waiting for Tehran's response to the final draft submitted by EU foreign policy chief Josep Borrell on August 8. US State Department spokesman Ned Price said Monday that Washington was informing Borrell of its views.

An unidentified Iranian diplomat said, according to IRNA, that "the European Union's proposals are acceptable provided that they provide assurances to Iran on various points, related to sanctions and safeguards" as well as pending issues with the International Atomic Energy Agency.

Britain, China, France, Germany, Iran and Russia, as well as the United States indirectly, resumed talks on the nuclear accord earlier in August after a months-long hiatus.

The EU-coordinated negotiations to revive the so-called JCPOA began in April 2021 before coming to a standstill in March.

The EU said last Tuesday it expected Tehran and Washington to "very quickly" respond to the "final" text aimed at salvaging the deal.

Iran's Foreign Minister Hossein Amir-Abdollahian said that, after the lengthy negotiations, "what counts for us is verification" that sanctions are lifted in practice.

The US State Department spokesman said it was up to Iran to make a final deal, rejecting reported demands that are outside the scope of the negotiations.

"We do believe that what could be negotiated has been negotiated, and we're prepared to affect a mutual return to compliance with the JCPOA," said Price.