The amount of rubbish on the UK's beaches has reached its highest level ever, according to a survey.
The Marine Conservation Society found that litter has increased by 110% since 1994 to 2,195 pieces per kilometre.
The society said the rubbish can harm wildlife and wants the government to develop a "co-ordinated marine litter strategy" to tackle the problem.
But the government has dismissed the call for a new approach, saying it is an "issue of personal responsibility".
Emma Snowden, a co-ordinator at the Marine Conservation Society (MCS), said: "Litter can harm and kill wildlife through ingestion and entanglement but it can also be harmful to people."
She added that it costs millions to clear from the coastline, discourages tourists and can damage fishing equipment.
More than 5,000 volunteers took part in the MCS annual Beachwatch survey.
Between them volunteers removed in excess of 385,000 pieces of litter from more than 370 beaches last September.
On average they picked up two pieces of rubbish a metre.
Compared to 2007, average levels rose in all areas of England except the north-west. Beaches in the south-west of England suffered from the highest density of rubbish at 4,784 items per kilometre.
In Northern Ireland, Scotland and Wales volunteers collected fewer pieces of litter this year, although Scotland had the highest litter average of the countries and regions surveyed.
'No action plan'
Bits of plastic were the most frequently found items, contributing to a 148% rise in the density of plastic waste since the survey began in 1994.
More than a third of the litter found was dropped by the public. The rest came mainly from fishing, sewage and shipping. Some items of rubbish, such as polystyrene and rubber fragments, could not be sourced.
Emma Snowden said everyone could play a part in cleaning up the coastline.
"This is a man-made problem. Every piece of litter has an owner and we all need to take responsibility to not drop litter in the first place."
But the MCS has also criticised the government for not having a co-ordinated response to the issue.
It wants specific bodies to be established in England, Wales, Scotland and Northern Ireland which would work together to deal with and prevent marine litter.
The society has set up a petition calling for a government action plan but ministers say individuals should be held responsible for dropping litter.
Environment minister Huw Irranca-Davies said: "Litter goes in our bins, not on our beaches - and ultimately this is an issue of personal responsibility.
"This is a problem caused by a minority who spoil things for everyone else, and campaigns against this behaviour can help us to make this unacceptable to everyone.
"That's why we fund Keep Britain Tidy for anti-litter campaigns to help stamp out the problem."
The Keep Britain Tidy campaign administers the Blue Flag and Quality Coast Award schemes in England.
The number of Blue Flag beaches in England has almost doubled over six years to 82 in 2008 compared with 45 in 2002. In Wales 42 beaches were awarded Blue Flags last year and in Northern Ireland seven beaches were recognised. Six Scottish beaches met the criteria.
Blue Flag status is awarded to beaches which meet high standards for water quality, environmental management, access and facilities.