PLANS to tax shoppers 10p for every plastic carrier bag they use in order to cut waste were yesterday attacked by retailers as a green light for shoplifting.

The Scottish Retail Consortium said if it became normal for shoppers to carry goods out of stores in their hands, thieves would take advantage.

The warning came after the launch of a member's bill at the Scottish Parliament which aims to create an environmental levy of 10p per plastic bag given out in shops and supermarkets.

The intention is to cut waste, raise money for green education and spare thousands of animals from death caused by eating plastic or becoming entangled in it.

Mike Pringle, LibDem MSP for Edinburgh South, said his bill had been inspired by a similar levy introduced in Ireland in 2002.

Bag consumption fell by 90-per cent after customers took to buying sturdier reuseable bags.

His Plastic Bags (Scotland) Bill now goes out to consultation, with MSPs due to take evidence on the plan in the autumn. If Holyrood endorses it, the bill could become law late next year.

Each of Scotland's 32 councils would then collect the levy, and spend the money on improving the environment.

Fiona Moriarty, director of the Scottish Retail Consortium, claimed store theft had risen in Ireland after the tax began there. "Last year alone retailers doubled their expenditure on crime prevention methods. Is Mike Pringle now asking us to increase spending by this amount again?" she said. "This is just another burdensome initiative. . . (that) will be difficult and expensive to police."

Peter Woodall, of the Carrier Bags Consortium, said Mr Pringle's argument was "the very worst case of junk science".

He claimed that if people switched to biodegradable paper bags, these would then decompose to create "clouds of methane over Scotland", worsening the greenhouse effect.

However, Mr Pringle, who has been backed by environment groups, said the Irish experience had been very positive - generating large amounts of money for projects, and encouraging the use of "bags for life" instead of throwaways. He said: "Scotland uses one billion plastic bags every year. They cause litter on our beaches, they are a danger to wildlife, and they all end up in a landfill site.

"By placing a small charge on each bag shoppers will only take those that they need."

An estimated one million birds and 100,000 marine mammals and turtles die every year around the world from eating or becoming entangled in plastic.

In 2002, a dead Minke whale found in Normandy was found to have 800kg of plastic bags, including some from UK supermarkets, in its stomach.

Last year, the Marine Conservation Society's beachwatch survey recorded a plastic bag for every 38 metres of Scottish coastline. Dan Barlow, head of research at Friends of the Earth Scotland, said: "Single-use carrier bags are symbolic of our wasteful attitude to resources. If the rest of the world consumed resources like the people of Scotland do, we would need two more planets to sustain us."

Laura Bateson, of WWF Scotland and the Scottish Wildlife Trust, added: "Plastic bags are a real and tragic threat tomarine life and it's deeply disturbing to think of the suffering animals face.

"By reducing the amount of plastic bags we use and discard in Scotland, we can make a real difference in protecting vulnerable marine animals."

The Scottish Greens said that, given the LibDems had recently backed GM crops and the M74 motorway extension, it was about time they did something right. Cosla, the council umbrella group, also backed the bill, but said any levy ought to be UK-wide.