People walk past Palais Coburg, where closed-door nuclear talks take place in Vienna, Austria, Dec 17, 2021. (MICHAEL GRUBER / FILE / AP)

TEHRAN - Iran said on Thursday that the Vienna talks on reviving the 2015 nuclear deal are in the "final critical steps."

"Nobody can say the deal is done, until all the outstanding remaining issues are resolved," Iranian Foreign Ministry's spokesman Saeed Khatibzadeh tweeted.

"Extra efforts needed. Everybody is now focused on the final critical steps," he said.

His remarks came after Western media reported that Iran and the parties to the 2015 Iranian nuclear deal, formally known as the Joint Comprehensive Plan of Action, are "very close" to an agreement.

"Premature good news does not substitute good agreement," the Iranian spokesman said.

ALSO READ: Iran FM: Vienna talks not over, US must make tough decisions

Iran and the remaining parties to the JCPOA, namely Britain, China, France, Russia and Germany, have held eight rounds of talks in Vienna in a bid to revive the deal, from which the United States unilaterally pulled out in 2018.