The Ukrainian navy has accused Russia of firing at some of its ships in the Kerch Strait. Hostilities ramped up when Russia blocked off the narrow channel of water after three Ukrainian navy ships made an 'unauthorised crossing’. The Russian coastguard was filmed ramming one of Ukraine's navy tugboats before opening fire on it and two artillery boats. 'Intercepted video' showing the tugboat being rammed by the Russia border service has been shared by Ukraine's Interior Minister. Arsen Avakov described it as a an act of aggression that 'will be used as proof in international court'. 'Russian coast guard vessels ... carried out openly aggressive actions against Ukrainian navy ships' during the transit, the Ukrainian navy statement said. It said a Russian coast guard ship damaged the tugboat's engine, hull, side railing and a lifeboat. The ships were travelling from Odessa on the Black Sea to Mariupol in the Sea of Azov. The Kerch Strait is the only passage into the Sea of Azov beyond it. It follows months of growing tensions between Ukraine and Russia, which annexed Crimea from Ukraine in 2014. Original Article: http://www.dailymail.co.uk/news/artic... Original Video: http://www.dailymail.co.uk/video/news... Daily Mail Facebook: / dailymail Daily Mail IG: / dailymail Daily Mail Snap: / 8392137033 Daily Mail Twitter: / mailonline Daily Mail Pinterest: http://pinterest.co.uk/dailymail Daily Mail Google+: https://plus.google.com/+DailyMail Get the free Daily Mail mobile app: http://dailymail.co.uk/mobile