Nearly 10,000 small plastic items were found, many of them industrial pellets which fish and seabirds can mistake for food, putting themselves at risk of being poisoned by chemicals which attach themselves to the plastic.

It's not only sewage that threatens marine life

Beach visitors are the largest source of rubbish, but the litter also comes from fishing boats, cargo ships and items such as cotton buds flushed down the toilet.

The director of conservation at the Marine Conservation Society, Sam Pollard, said: "We are pleased to see that the levels of litter have decreased for a second consecutive year and we hope that this trend continues.

"But we as individuals must safeguard the environment and wildlife by taking care with our litter."

Among the litter picked up in this survey were a fridge door, a number 49 lottery ball, and a shampoo sachet dating from before the introduction of decimal coinage 30 years ago.