Banish the bags: The National Trust backs the Mail campaign to end blight on countryside

Carriers can be found in 9 per cent of public places, up from 7 per cent the year before.

And supermarket bags litter 5 per cent of these spaces, up from 4 per cent from 2006.

The Government survey lends urgency to the Daily Mail's campaign to banish the 13billion plastic carriers handed out in Britain each year.

They are used on average for just 20 minutes, but the effect on the environment lingers for hundreds of years.

Our campaign is gathering support from a growing number of retailers - and now the National Trust has also pledged its support.

A spokesman for the charity said: "From an environmental point of view plastic bags are putting our wildlife at risk.

"And from an aesthetic point of view they blight some of the most stunning views our country has to offer.

"This is why the National Trust is backing the Daily Mail's campaign to banish the bag.

"If retailers and consumers work together on taking this small step we can make an incredible difference to our countryside and our wildlife."

The Government's survey, for the Department for Environment, Food and Rural Affairs, looked at the litter in more than 300 sites across England.

It found that levels of gum, discarded food, cans and bottles had also risen.

However, ministers said there was less graffiti and dog fouling than in previous years, and that councils were doing more to keep streets clean.

Environment Minister Jonathan Shaw said: "This survey shows that we are making progress in some areas.

"But there is much room for improvement and we can't let up in the battle against this blight."

The Tories, however, said a budget crisis at Defra meant that spending on litter was being cut.

Peter Ainsworth, environment spokesman, said: "This is further proof of how out of touch the Government has become, the very moment when the public are demanding action on litter and plastic bags, Defra has cut support for local litter reduction schemes.

"While ministers attempt to spin this survey as good news, the truth is that over the past year, more and more places in England were considered to have unacceptable levels of litter, graffiti and detritus."

Conservationists and scientists say plastic bags are a menace in the countryside.

A United Nations report in 1987 found plastic kills about 100,000 sea turtles, whales, dolphins and other animals each year.

Today's figure is thought to be much higher. Plastic waste also kills an estimated one million birds annually.

Plastic bags are a particular danger to turtles, which mistake them for jellyfish.

Last week, a post-mortem examination on a leatherback found in Strangford Lough, Northern Ireland, found plastic bags in its stomach.

Bookstores are eager to play their role in reducing the amount of bags handed out.

Waterstone's and Borders have told staff not to hand out bags without first asking customers. The stores will also encourage shoppers to take new re-useable bags.

Waterstone's says it is rolling out a £2.99 canvas bag at its 320 stores within weeks.

Borders, which has about 70 stores, says it will have a fully recycled and biodegradable plastic bag in its stores by May.

The National Trust, one of the world's biggest conservation charities, with 3.5million members, is also considering the future of plastic bags in its shop.

In May, Marks&Spencer will stop giving away free bags at food stores. Soon after, it will charge 5p for each plastic bag.

B&Q is introducing charges for bags after a trial saw the number used fall by up to 88 per cent.

Debenhams and Woolworths have also pledged to scrap free bags and will introduce charges during trials over the next few months.

Asda is removing all dispensers of single-use carrier bags from its checkouts after a trial in six stores led to a 20 per cent fall.

Customers will have to ask for a bag if they need one. Sainsbury's is instructing staff to offer re-useable bags to all its customers.

A voluntary ban by supermarkets in France has virtually eliminated free bags. And in Ireland, a plastic bag tax led to a 93 per cent reduction.

The Mail's campaign has won the support of Prime Minister Gordon Brown, Tory leader David Cameron and LibDem leader Nick Clegg.