Earlier this week Reuters, citing six sources, reported that Iran had provided Russia with a large number of powerful surface-to-surface ballistic weapons to Russia, deepening military cooperation between the two U.S.-sanctioned nations.

The Biden administration warned Iran on Thursday of a "swift and severe" response from the international community if the Islamic Republic had provided ballistic missiles to Russia.

"Despite no legal restrictions on ballistic missile sales, Iran is morally obligated to refrain from weapon transactions during the Russia-Ukraine conflict to prevent fueling the war," Iran's mission to the United Nations said on the X platform.

"(That) is rooted in Iran's adherence to international law and the UN Charter," it added.

U.N. Security Council restrictions on Iran's export of some missiles, drones and other technologies expired in October.

However, the United States and the European Union retained sanctions on Iran's ballistic missile programme amid concerns over exports of weapons to its proxies in the Middle East and to Russia.

Iran initially denied supplying drones to Russia but months later said it had provided a small number before Moscow launched its invasion of Ukraine on Feb. 24, 2022.

(Reporting by Dubai newsroom; Editing by Gareth Jones)