Shoppers could be charged 20p for plastic carrier bags at checkouts under proposals put forward by a committee of AMs today.

The Sustainability Committee says the fee would raise about £13 million a year for environmental causes and cut litter by encouraging people to keep reusable bags.

It rejected calls for an outright ban because it would be too difficult to enforce, especially along the border with England if Wales went it alone, committee chairman Mick Bates said.

He said legislation going through Parliament would give Welsh ministers the power to impose a levy on bags, 648 million of which are used in Wales every year.

A committee report gives examples of how much would be raised, starting with £6.48 million if bags cost 10p each.

Marks & Spencer began charging customers 5p for carrier bags this year.

AMs were impressed by a similar bag tax in Ireland which had cut their use by 90%, Liberal Democrat AM Mr Bates said.

He said: "We decided a ban was going to be difficult to implement and that the evidence, particularly from Ireland and Marks & Spencer, found a levy was very helpful to do good environmental works with.

"There's great benefit from a levy because some people would say what's 20p, what's 10p to get a bag? It's a one-off if I have forgotten my hessian shopping bag.

"You're reducing the environmental impact that occurs from litter and at the same time you're raising that money.’’ He said cutting back on plastic bags might mean job losses for workers employed in manufacturing them, but added: "We have got to be brave.

"We are concerned about the impact (of bags) like killing animals because a lot of animals die from ingestion.’’