Iran’s foreign minister said on Friday he was prepared to go to Vienna

“immediately” to sign a deal with the US to revive the 2015 nuclear accord, but warned he would only do so if western negotiators agreed to meet Tehran’s outstanding demands.

The comments from Hossein Amirabdollahian came as western officials suggested they were inching closer to securing an agreement at indirect talks between Tehran and the Biden administration in the Austrian capital. But they are also pressuring Iran to quickly agree on final issues after 11 months of negotiations to save the accord abandoned by then US president Donald Trump.

“We are ready to finalise a good agreement immediately. . . but the western parties’ rush to conclude a deal cannot prevent Iran’s red lines from being observed,” Amirabdollahian told the EU, according to Iran’s foreign ministry. “I am ready to go to Vienna as soon as western parties accept to observe our remaining red lines.”

The deal’s signatories also include Germany, France, UK, Russia and China. Western officials have been warning for weeks that time is running out to save the deal because of the scale of Iran’s nuclear advances, with the Islamic republic enriching uranium close to weapons-grade. But Tehran has insisted it will not seal an agreement at any cost and will not be rushed.

A US state department spokesperson said on Thursday that there had been “significant progress” at the talks, adding that “if Iran shows seriousness, we can and should reach an understanding of mutual return to full implementation” of the accord “within days”.

But she warned that “a number of difficult issues still remain unsolved”.

Stephanie al-Qaq, a senior British diplomat at the talks, said on Friday “we are close” to a deal, adding that European officials were briefly leaving Vienna to update their ministers.

Rafael Grossi, head of the International Atomic Energy Agency, was scheduled to be in Tehran on Saturday to discuss one of the points holding up progress at the talks: a dispute over a stalled probe by the UN’s nuclear watchdog into traces of uranium found at old, undeclared sites.