Read our Privacy noticeThe Royal Navy has warned of a significant increase in Russian naval activity near UK waters, having spent 21 days in July monitoring Moscow's vessels. Offshore patrol vessels HMS Tyne, HMS Mersey and HMS Severn were deployed throughout the month to monitor Russian frigates Neustrashimy and Admiral Grigorovich, which are tasked with escorting so-called “shadow fleet” tankers. Russia uses its ageing shadow fleet to evade international sanctions on its oil exports and help fund its war in Ukraine. The increase in Russian naval activity follows the seizure of the tanker Smyrtos by Royal Marines in June, the first time British troops have directly boarded a shadow fleet vessel. The Ministry of Defence (MoD) said the diversion of Russian ships to escort shadow fleet vessels meant Russia was “using up valuable operational capacity to constantly guard cargo”.