"This topic was touched on... in the context of mediation efforts by Oman," Kremlin spokesman Dmitry Peskov told reporters, including AFP, during a briefing at the Kremlin.

Russia has welcomed the surprise talks between Washington and Tehran over Iran's nuclear programme, which is being mediated by Oman.

"Russia is ready to do everything that depends on it to contribute to a fruitful and active conclusion of these talks," Peskov said, repeating Russia's oft-stated position.

Donald Trump pushed Iran to open negotiations on limiting its nuclear weapons development programme, after he pulled out of the landmark US-Iran nuclear deal during his first presidency.