Royal Navy warship HMS Somerset has shadowed a Russian submarine as it passed through the English Channel.
The Plymouth-based ship located the Kilo-class diesel-electric submarine Krasnodar in the early hours of Friday morning as it sailed past the Britain's eastern coast.
HMS Somerset, a Type 23 frigate, then followed her through the Dover Strait and the rest of the English Channel over the weekend.
Commander Tim Berry, Commanding Officer of HMS Somerset, said:
"Policing the sea both in home waters and further afield is core business for the Royal Navy. Escorting foreign warships, in this case a Russian submarine, through UK waters is just part of our ongoing effort to protect our island nation."
Last month, Somerset's sister ship HMS Sutherland was called on to escort two Russian warships as they sailed close to UK territorial waters.
When on patrol in domestic waters, HMS Somerset can be called upon at any time to help prevent arms trafficking and people smuggling, and to conduct counter-terrorism operations, maritime search and rescue, or escort duties like those it has undertaken this weekend.