Watch: Ukrainian sea drone targets Russian tanker

This is the moment a naval drone purportedly heads directly towards a Russian tanker in the Kerch Straight, south of the Crimean Bridge.

Unverified footage shared by a source at Ukraine's security service shows what they say is the drone moving across the Black Sea, as it approaches the Russian vessel.

Russian maritime officials said the Sig tanker's engine room was damaged in an attack, but no-one on board was injured.

A Ukrainian security service source told the BBC the operation was conducted jointly with the Ukrainian navy and that 450kg of TNT explosive had been used.