The Government’s plans for a 5p plastic bag charge have been branded a “complete mess” by a cross-party committee of MPs.

The Environmental Audit Committee (EAC) has said the current plans are “unnecessarily complicated” because they exempt smaller retailers from the charge.

In September last year deputy prime minister Nick Clegg revealed plans to introduce a single-use plastic bag charge in England in 2015 to tackle the more than eight billion disposable carrier bags which are used in England every year.

But the EAC are concerned about the planned exemptions drawn up by the Department for the Environment, Food and Rural Affairs (DEFRA), which state that the 5p charge will only apply to supermarkets and larger stores.

Most small shops would not have to pay the cost, as DEFRA believes that the charge should not be a burden to small businesses.

DEFRA also wants to exempt paper bags and reusable ‘bags for life’ but the EAC believe these rules are making the proposal too complex, according to the BBC.

EAC chair Joan Walley said: “Ministers have managed to make a complete mess of their planned carrier bags charge by making it unnecessarily complicated.

“Carrier bags litter our streets and harm wildlife, and the government is right to want to reduce their use. But DEFRA seems to have made decisions about the design of this scheme that were based more on wishful thinking than hard evidence.”

The Association of Convenience Stores said the best way of tackling the issue was to ensure that every shop is charged for plastic bags.

A Defra spokesman defended the planned exemptions. He said: “Paper bags make up only a small proportion of carrier bags and break down naturally. Biodegradable bags will only be exempt if they are genuinely biodegradable - currently such a bag does not exist.”

It emerged this week that environment minister Dan Rogerson had miscalculated the climate change benefit of the levy. He said the charge would cut carbon emissions by the equivalent of 2.2m cars. The correct number was 37,500.