Attracted by rubbish being dumped by the crew of the sub, the bear attempts to clamber aboard

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The sub was put into lockdown while crew waited for the 65st bear to lose interest in the vessel. The Delta IV class sub is believed to have been patrolling north of the Norwegian islands of Svalbard and Jan Mayen when it surfaced through thick ice to dump bags of rubbish. Its crew had no idea that they had been spotted by a polar bear which pawed its way on to the sub's casing deck as it searched for more bags of rubbish, while the vessel's 120 sailors were ordered to remain below decks.

Norway and Russia share a population of 3,000 polar bears that are migrating on the ice from Spitsbergen in the west to Novaya Zemlya in the east, but increasing litter is threatening the region with ecological disaster. In 2015 Russian submariners experienced a similar surprise, also after disgorging rubbish, and experts say the country's pollution in the Arctic would take hundreds of years to clear up. A Royal Navy source said: "We stick completely to maritime law and have systems in place to sort, recycle and dispose of rubbish in an environmentally friendly way.

POLAR EXPLORER: The Russian submarine surfaces near a waiting polar bear