By Alex Kirby BBC News Online environment correspondent

UK beaches are popular - and often filthy

The survey, in September 2002, found litter levels were slightly above the previous year's, and more than half as great again as in 1994.

It found one piece of litter for every 60 centimetres (24 inches) of beach inspected.

But it recorded the lowest levels of sewage-related debris ever found.

The survey was completed by 2,598 volunteers for the Marine Conservation Society (MCS). They searched 229 beaches, stretching for 150 km (93 miles), on 21 and 22 September 2002.

The volunteers found 241,285 separate pieces of litter, 2.1% more than in 2001. But litter from sewage made up only 3.9% of the total, compared with 6.7% in 2001.

Ubiquitous bags

The 10 commonest items found represented 61% of all litter collected, and included categories such as plastic drinks bottles, cigarette stubs, crisp and sweet wrappers, and glass pieces.

Litter from sewage was less of a problem

MCS says plastics were again the material found most often, accounting for at least 57% of the total.

Finds included 36 plastic bags for every kilometre of coastline surveyed and MCS wants the government to introduce a plastic bag tax.

Alison Conway of MCS said: "The amount of litter collected in 2002 shows a 2.1% increase on 2001 levels.

"Although that's only a slight increase, litter levels are over 50% higher than those recorded in 1994, indicating there is still a long way to go to ensure our beaches are clean and safe places for people and wildlife.

Expensive habit

"Litter poses a threat to dolphins, whales, turtles and seabirds by entanglement in and ingestion of plastics.

Plastic litter helped to kill a whale

"It also spoils fish catches, and affects local economies through clean-up costs and loss of tourism in affected areas."

A dead minke whale found on a beach in Normandy, in France, in April 2002 had 800 grammes (1.7 pounds) of plastics in its stomach. They included two English supermarket bags and a British plastic and foil potato crisp wrapper.

The survey found the highest proportion of litter was left by beach visitors (39.1%), followed by fishing litter (14.6%), sewage-related debris (3.9%), and shipping (2.2%).

Long-lived hazards

Seb Clover, the youngest person to make a solo Atlantic crossing, said: "When I set off in December 2002, the first few miles of my trip were fraught with danger - not from the usual hazards that one always expects at sea - but from fridges and all sorts of other floating rubbish which surrounded Tenerife.

"Even in mid-ocean you see lots of rubbish just floating about. Plastics float around for years without degrading and you see lumps of polystyrene regularly.

"Much of it ends up on beaches the world over. It is about time we stopped treating our world so badly - it's the only one we've got."