Washington has walked back earlier charges of an imminent weapon sale to Russia

Iran has since ramped up some nuclear activities, putting a ticking clock on an attempt to return to a deal in talks between Western powers and Tehran in Vienna.

France is among world powers trying to revive a 2015 nuclear deal with Iran that the previous U.S. administration quit and which Israel opposed, deeming its caps insufficient.

Foreign Minister Hossein Amir-Abdollahian had said Iran was "serious" about finalising a deal in Doha, but that it wouldn't cross its "red lines".

Tehran for its part said its focus was on sanctions relief, not directly mentioning the nuclear deal.

Russia played a key role in that deal, taking charge of Iran's excess enriched uranium stocks beyond those permitted under the agreement.

The US decided again to prolong and delay the agreement and went to the (IAEA) board of governors meeting with the delusion of using leverage

The United States is pursuing the path of meaningful diplomacy to achieve a mutual return to compliance with the Joint Comprehensive Plan of Action

The Guards accused "Zionists" of being behind the high-profile assassination and vowed revenge.

"We urge Iran to heed the call of the international community to fulfil its legal obligations, and cooperate with the IAEA to fully clarify and resolve issues without further delay."

IAEA board of governors meeting in Vienna likely to adopt anti-Iran resolution

A deal was reached about two decades ago to allow Iran to supply Oman with gas, but the project never materialised.