Prime Minister Gordon Brown has pledged to introduce legislation if necessary to impose a minimum 5p charge on supermarket plastic bags.

Retailers will be given a year to end use of single-use bags or be forced to introduce a charge for them and to reveal how much money this raises.

The clarion call followed yesterday’s unilateral decision by Marks & Spencer to introduce a 5p charge on its bags from May, with the revenues going to green charities.

About 13 billion bags are handed out each year, despite a voluntary industry pledge to reduce their use by 25 per cent.

Under amendments to the Climate Change Bill, the Government is expected to introduce a mandatory fee for disposable bags and give ministers the power to require supermarkets to declare how much they raise each year from the levy. The legislation could be introduced as early as next month.

Although the big supermarket groups have pledged to reduce their use of disposable bags, sell “bags for life” and, in Tesco’s case, offer Green Clubcard points for customers reusing disposable bags in stores, the Prime Minister is understood to be frustrated at the pace of reduction.

“Plastic bags are one of the most visible and easily reducible forms of waste and cutting them out of our lives is one of the most straightforward ways we can all do something directly to improve our environment and reduce pollution,” the Prime Minister said.