US Secretary of State Antony Blinken said Friday he discussed Iran with his Russian counterpart, warning there was only a brief window to succeed in Vienna talks.

Blinken told reporters the 2015 nuclear deal (JCPOA) was an example of how Moscow and Washington can work together on security issues, urging Russia to use the influence it has and its relationship with Iran to impress upon Tehran the sense of urgency.

Blinken said there was still a window to return to the deal - which has unraveled since 2018 when then-US President Donald Trump abandoned it - but warned that Tehran's continuing nuclear advances would foil any return to the accord if a fresh pact was not reached in coming weeks.

"The talks with Iran about a mutual return to compliance with the JCPOA (2015 deal) have reached a decisive moment," Blinken said.

"If a deal is not reached in the next few weeks, Iran's ongoing nuclear advances will make it impossible to return to the JCPOA. But right now, there's still a window, a brief one, to bring those talks to a successful conclusion and address the remaining concerns of all sides."

The US and its European allies said on Thursday it was now just a matter of weeks to salvage the deal after the latest round of talks in which a French diplomatic source said there had been no progress on the core issues.

Report by Reuters