The Liberal Democrats would remove all exemptions for plastic bag charges in the next parliament, meaning small stores would also be required to apply a 5p levy.

A 5p charge for single use carrier bags will be introduced in England in October, but businesses with less than 250 employees will be exempt from applying the charge.

But Liberal Democrat leader and deputy prime minister Nick Clegg said his party would remove all exemptions through a new Nature Bill in the next parliament.

He said restrictions on plastic bag charges were imposed by the Conservatives in coalition, despite backing for a universal levy from NGOs, consumers and business groups.

“The facts are simple; single use bags blight our towns and countryside, they trap and suffocate wildlife, and plastic bags take hundreds of years to degrade,” he said.

“The countdown to charging has begun, and by the time it arrives this autumn, reusable bags should increasingly be commonplace. As we get used to it, the hundreds of millions raised from the charge will go to charities.”

The Association of Convenience Stores and a number of independent retailers have long called for small shops to be included in the charge. The experience of retailers in Wales, where a 5p levy was introduced in 2011, has been overwhelmingly positive.