Plastic bottles found round the UK's beaches could take up to 500 years to break down once in the sea, which campaigners claim strengthens their case for bottle deposit return schemes (DRS) round the country.

Over 8,000 plastic bottles were found on UK beaches during just one weekend, according to the latest beach litter figures from the Marine Conservation Society (MCS) published today.

On average, 99 bottles were picked up along every kilometre cleaned along 340 beaches from Orkney to the Channel Islands during the MCS Great British Beach Clean last September.

The charity’s report, also claims a shocking 34 per cent rise in beach litter overall between 2014 and 2015, a record breaking number of volunteers taking part, just over 6,000, and the largest amount of litter found per kilometre was a "staggering 3,298" pieces.

There was a big percentage rise in most drinks containers, found on beaches between 2014 and 2015. Plastic drinks bottles increased by over 43 per cent, metal drinks cans by almost 29 per cent, and drinks container caps and lids were up by over 41 per cent. Only glass bottles went down and that was only by less than 1 per cent.

Plastic bottles on beaches rose by 6.3 per cent in the Channel Islands, 57.2 per cent in England, 21.3 per cent in Scotland and by an extraordinary 235.3 per cent in Northern Ireland. In Wales they dropped by 39.4 per cent but that’s in line with the overall drop in the country’s litter levels, but there were still 103 plastic bottles found per km cleaned, which is higher than the national average.

“There have been increases in the number of plastic bottles found on beaches in England, Scotland, Channel Islands, and Northern Ireland”, said Lauren Eyles, MCS Beachwatch Manager. “Only Wales has bucked the trend in 2015 but that’s almost certainly as a result of very high levels in 2014, where more bottles were found on Welsh beaches than anywhere else. The bottles we find on beaches are either dropped directly onto the beach, blown from land or sea, or end up there via rivers. The more we use as a nation, the more we’ll see ending up on our shores.”

In Scotland, MCS is a founding partner of the ‘Have you got the bottle’ campaign led by the Association for the Protection of Rural Scotland (APRS). The idea is to charge shoppers a deposit when buying products in cans and plastic and glass bottles, which would then be refunded when they return the empty containers. There used to be deposits on the likes of glass lemonade bottles, but they have long since been removed.

Calum Duncan, MCS Head of Conservation in Scotland. said: “We’re confident that evidence from other countries and a successful trial at Heriot-Watt University shows that a Scotland-wide roll-out of a DRS would lead to reduction in the number of drinks containers that blight our beaches. A survey for APRS showed that 78.8 per cent backed a DRS for Scotland. With countries like Germany, where DRS was introduced a decade ago, recycling near to 99 per cent of drinks containers, it’s not difficult to see why support is growing for this proven system.”

MCS's beach-cleaning work is supported by the Peoples Postcode Lottery, whose Head of Charities for People’s Clara Govier, said: “Players of People’s Postcode Lottery will be glad to know the money they raise is helping to make our beaches cleaner.”