A convoy has been spotted transporting equipment for Russia's nuclear weapons programme, prompting fears that Vladimir Putin could be preparing a test to send a "signal to the West".

The pro-Russian Telegram channel Rybar shared the footage, which showed the freight convoy hauling upgraded armoured personnel carriers (APCs) and other equipment.

Konrad Muzyka, a Poland-based defence analyst specialising in Ukraine, said: "This is kit belonging to the 12th main directorate of the Russian MoD.

"The directorate is responsible for nuclear munitions, their storage, maintenance, transport, and issuance to units."

Muzyka added it could be a "signalling to the West that Moscow is escalating", in reference to Putin's nuclear-war threat on Friday. However, he stressed that the video did not show "preparations for a nuclear release".