A view shows a residential building destroyed by a Russian drone strike, which local authorities consider to be Iranian-made Shahed-136 unmanned aerial vehicles (UAVs), amid Russia’s attack on Ukraine, in Kyiv, Ukraine on 17 October, 2022

France, Britain and Germany called Friday in a letter to the United Nations for an “impartial” investigation into Iranian drones the West says Russia is using in the war in Ukraine.

“We would welcome an investigation by the UN Secretariat team responsible for monitoring the implementation of UNSCR 2231,” the UN ambassadors of the three countries wrote.

UN Security Council Resolution 2231 endorsed the international agreement that provided for sanctions relief in exchange for curbs on Iran’s nuclear programme -- a deal that was later scrapped by then-US president Donald Trump.

In their letter, which was addressed to the Security Council and Secretary-General Antonio Guterres, the ambassadors said they would “stand ready to support the work of the Secretariat in conducting its technical and impartial investigation.”

Drones are seen during a large-scale drone combat exercise of Army of the Islamic Republic of Iran, in Semnan, Iran on 4 January 2021

They added that they were “deeply concerned by the transfer of unmanned aerial vehicles (UAVs) from Iran to Russia in violation” of the resolution.

“These UAVs are being used by Russia in its war of aggression against Ukraine in attacks against civilian infrastructure and cities across Ukraine, leading to the death of innocent civilians,” they wrote.

French ambassador to the UN Nicolas de Riviere called on Iran “to immediately cease all forms of support to Russia’s aggression on Ukraine.”

A device, that Anti-aircraft units of the Ukrainian Air Forces who operate in Southern Ukraine hit and identified as an Iranian-made Qods Mohajer-6 UAV, which then was found and captured in waters, is seen floating in an unconfirmed location in this screen grab taken from a handout video released on 23 September, 2022

Western countries have accused Iran of supplying drones that Moscow is using to carry out strikes in Ukraine, and the White House said Thursday that Iranian personnel were on the ground in Crimea helping Russian forces conduct drone attacks.

However, Russia’s UN envoy, Vassily Nebenzia, called the charges “another fake (news) about the alleged supplies to Russia... We reject any attempts to involve the UN secretariat in this dirty undertaking.”

Iran also strongly rejected the drone allegations at the United Nations earlier in the week.