Media playback is unsupported on your device Media caption Ed Davey: "Try to avoid this charge, we want you to re-use your plastic bags"

A 5p charge for plastic bags in England is to be introduced by the government in a bid to discourage their use.

Deputy Prime Minister Nick Clegg is to unveil the plans at the Liberal Democrat party conference this weekend.

Ministers are said to be concerned at the environmental impact of the bags, particularly on waterborne animals.

The charge, which will only apply to supermarkets and larger stores, will begin after the 2015 election, with the proceeds going to charities.

A similar charge applying to the single-use carrier bags made from both plastic and paper is already in effect in Wales and Northern Ireland.

Northern Ireland's Environment Minister, Mark H Durkan, this week announced he was not going ahead with plans to raise the levy to 10p per bag, because the present arrangements were proving successful.

He said data from major supermarkets showed there had been an 80% reduction in plastic bag use since the levy was brought in.

Retailers in Scotland will start charging for bags in October 2014.

According to Liberal Democrat sources, the charge in Wales, which began in 2011, has seen the use of plastic bags drop by roughly 75%.

Liberal Democrat Energy and Climate Change Secretary Ed Davey said his party had faced opposition to the scheme from the Conservatives.

He said the charge would only raise "pretty small amounts" for charity, as its intention was to get people to reduce the amount they use.

Speaking to BBC Breakfast, he said: "It is a huge environmental step forward.

'Tough times'

"We are very clear that none of this money will come to government, we are not trying to tax people, we are trying to change people's behaviour, encourage much more environmentally-friendly behaviour."

This small step will do little to tackle the nation's huge waste mountain Craig Bennett, Friends of the Earth

Deputy Prime Minister Nick Clegg said there was enthusiasm for the plans among major retailers but there had been opposition from government colleagues.

Speaking on a visit to Cathkin Marsh nature reserve, near Glasgow, he said that plastic bags were often used for just a few minutes but "take 1,000 years to degrade".

He said: "That's not just bad for the environment, they are a terrible eyesore on our beautiful countryside. They cause a lot of suffering for animals, particularly marine wildlife."

Mr Clegg said he hoped any money raised by the levy would be donated to environmental charities.

He added: "Of course there are debates in government on something like this, this is a big change. But it's one that I was very keen to do and I think we will now do it - not overnight, it will happen by the end of 2015.

"But I think very quickly, just as in the way people are accepting it in Wales where there has been an up to 80% drop in the use of plastic bags, people will get used to it and support it."

Andy Walker from the campaign group, Keep Britain Tidy, said that free plastic bags came with a "cost to the environment".

"Our supporters up and down the country end up cleaning bags from water courses, from beaches, from the High Street... so we believe it'll reduce the incidence of bags there," he said.

"But it will also influence behaviour change - people will start to take reusable bags with them to the supermarket and that will actually make a big difference to the environment."

But Matthew Sinclair, from the Taxpayers' Alliance, said the charge was an unnecessary measure that would have little impact on overall waste.

"This is not just a small share of waste, this is a tiny share of waste," he said.

"And I don't think that for every problem the answer is a new tax.

Image caption Supermarkets have already been encouraging customers to reduce their use of carrier bags

"There are already a number of different schemes to encourage people to think about using reusable bags, there are other schemes which involve using the carrot rather than the stick of a new tax."

Craig Bennett, policy and campaigns director of Friends of the Earth, said: "A plastic bag charge is welcome news, but let's not get carried away.

"This small step will do little to tackle the nation's huge waste mountain and can't disguise the government's woeful green record."

He said tougher action and ambitious targets were needed to to cut waste, boost recycling and "bring England in line with the rest of the UK and much of Europe".

BBC political correspondent Robin Brant said ministers acknowledged that shoppers may be unhappy about the prospect of the charge in what are "tough times" but the coalition believed it needed to tackle their use.

A number of supermarkets already encourage customers to limit their use of carrier bags by giving them loyalty points for providing their own. Marks & Spencer charges 5p for its plastic carrier bags, donating the profits to charities and education projects, but still gives out smaller bags.

Charities involved in clearing up the environmental damage caused by plastic bags will benefit from money raised by the new charge.

Groups such as the Campaign to Protect Rural England, Keep Britain Tidy, the Marine Conservation Society and Surfers Against Sewage have long called for a charge. They said plastic bags littered England's streets and countryside.

The bags, they say, have proved harmful to wildlife which become entangled in them or think they are food.