The seabed in the arctic deep ocean is increasingly strewn with litter and plastic waste, a German researcher says, with twice as much debris as ten years ago.

Marine biologist Melanie Bergmann of the Alfred Wegener Institute for Polar and Marine Research in Bremerhaven examined some 2,100 seafloor photographs taken near a deep-sea observatory in the arctic's eastern Fram Strait between Greenland and the Norwegian island of Spitsbergen.

"The study was prompted by a gut feeling. When looking through our images I got the impression that plastic bags and other litter on the seafloor were seen more frequently in photos from 2011 than in those dating back to earlier years," she said.

"For this reason I decided to go systematically through all photos from 2002, 2004, 2007, 2008 and 2011."

"Waste can be seen in around 1 percent of the images from 2002, primarily plastic. In the images from 2011 we made the same discovery on around 2 percent of the footage. The quantity of waste on the sea bed has therefore doubled," she said.

The increasing plastic contamination of the seafloor is affecting deep-sea inhabitants at risk, she said.

"Almost 70 percent of the plastic litter that we recorded had come into some kind of contact with deep-sea organisms. For example we found plastic bags entangled in sponges, sea anemones settling on pieces of plastic or rope, cardboard and a beer bottles colonized by sea lilies."

Bergmann's study has been published in the journal Marine Pollution Bulletin.