"We are convinced that there is still a chance to return the (Joint Comprehensive Plan of Action) into a stable situation," Russia's top diplomat said as he met with Iranian counterpart Mohammad Javad Zarif in Moscow.

"In any case, we will do everything to make it happen, just like our Iranian friends," he said.

Iran signed the agreement with the five UN Security Council members plus Germany in 2015, agreeing to limit its nuclear programme in exchange for sanctions relief, but the deal has been on life support since US President Donald Trump withdrew from it and unilaterally reimposed sanctions in 2018.

Iran has since taken small but escalating steps away from compliance with the nuclear accord as it presses for renewed relief from sanctions.

Both ministers remarked that the deal "turned five years old" last week, with Zarif calling it a "historical international agreement."

After the two greeted each other with an elbow bump, Zarif thanked Russia for its "remarkable" efforts to keep the deal alive.

Iran's economy has been hard-hit by the US sanctions, which have scared off most international banks and firms from re-engaging with Tehran, and it has been further battered by the coronavirus epidemic.