The Royal Navy has been monitoring a Russian spy ship after it entered British waters earlier this week, the defence secretary has told MPs. John Healey said the vessel, Yantar, was used for gathering intelligence and mapping the UK's critical underwater infrastructure.

A British official sent a public warning to Russian President Vladimir Putin on Wednesday after the Royal Navy started tracking the Russian spy vessel Yantar in British waters this week.

Britain said it monitored a Russian spy ship in the English Channel in recent days and would strengthen its response to secret operations by Russian ships and aircraft in an effort to protect undersea cables.