Russia has accused the United States of irresponsibly stoking regional tensions over Iran, with Foreign Ministry spokeswoman Maria Zakharova saying Moscow continues to see "unceasing threats" against Tehran on February 26.

The Russian official’s comments come as Iranian and American delegations sat down for a third round of indirect nuclear talks in Geneva, with no deal by 13:30UTC/GMT.

"We see unceasing threats against Tehran, sabre-rattling and intimidation, the irresponsible stoking of regional tensions by Washington," Zakharova said at a briefing on February 26.

"Despite this, Russia and Iran continue to steadily strengthen mutually beneficial cooperation in the interests of the peoples of both countries," TASS reported.

The remarks came as US and Iranian delegations arrived at the Omani ambassador's residence in Geneva, where Omani officials acted as intermediaries, moving between rooms to relay messages between the two sides.

Iran's Supreme Leader, Ayatollah Ali Khamenei, has ruled out direct talks with the US, making an indirect format necessary; however, commentators say the two sides are already talking directly despite claims to the contrary.

The talks are being led on the US side by special envoy Steve Witkoff and presidential adviser and Trump son-in-law Jared Kushner.

Iranian Foreign Ministry spokesman Esmaeil Baghaei said Tehran's delegation arrived fully prepared, with experts covering sanctions relief, economic issues, nuclear matters and legal affairs.

Before travelling to Geneva, Iranian Foreign Minister Abbas Araghchi said a "fair, balanced and equitable deal" was within reach, while reiterating that Iran was not seeking an atomic weapon and was not prepared to give up its right to the peaceful use of nuclear technology.

The first round of talks was held in Oman on February 6, followed by a second session in Geneva on February 17. Araghchi said afterwards that the two sides had reached a tentative understanding on road principles, though no substantive agreement had been reached.

Significant gaps remain. US Secretary of State Marco Rubio said the talks would focus primarily on Iran's nuclear programme and reiterated Washington's concern about Iranian ballistic missiles, which he said Tehran was attempting to develop into intercontinental-range weapons, calling Iranian insistence on excluding the missile programme from negotiations "a big, big problem." Iran has said its missiles are purely defensive.

The talks are viewed by many as a last chance for diplomacy as the US has assembled a fleet of aircraft and warships in the Middle East to pressure Tehran into a deal. Iran has maintained it wants to continue to enrich uranium even as its programme sits in ruins following Trump's order to attack three of the Islamic Republic's nuclear sites in June 2025.

Russia and Iran meanwhile held joint naval exercises in the Gulf of Oman and the Indian Ocean, with the drills intended to promote security and maritime cooperation, according to Iran's state-run IRNA news agency.

Zakharova had previously said Moscow was "confident that military pressure on Iran won't help resolve the situation but may intensify tensions across the entire Middle East," TASS reported on February 4.