Less than 8% of the food in the major UK chains is produced locally

Half the 1,000 people asked in the study said they were worried about supermarkets' size and strength driving independent high street traders out of business.

The poll, commissioned by think-tank the New Economics Foundation (NEF), also suggests customers want to buy food grown and produced in their local area.

But supermarkets have dismissed the poll findings and said consumers liked the better choice and convenience they provided.

The study said most people would prefer to shop in their own neighbourhoods rather than out-of-town stores.

Supermarkets are so big they can abuse their power in controlling supply chains NEF director of policy Andrew Simms

And one out of every five thought supermarkets had more influence over planning decisions than councils.

Although supermarkets say they are "customer led", less than 8% of the food in the major UK chains is produced locally.

And even that could contain ingredients from much further afield, the NEF researchers say.

NEF director of policy Andrew Simms told BBC News: "The phenomenon of ghost-town Britain - local shops and services losing out to larger operators - has drained High Streets of their vitality.

'No free choice'

"We have been on a downward curve for about 20 years and unless there are some changes to level the playing field for smaller shops, it is extremely likely to continue.

"People do not have a free choice because the supermarkets are so big they can abuse their power in controlling supply chains.

"They are also rather good at lobbying government and local planning authorities - the sort of thing small shops can't do."

Kevin Hawkins, communications director at Safeway, told BBC News Online consumers "vote with their feet".

Lots of supermarkets operate smaller stores and some of us never left the High Street Kevin Hawkins Safeway

"Supermarkets offer better value, more choice, and they are above all, more convenient.

"We don't seek to put small operators out of business. They were in decline long before large supermarkets appeared.

"But there are still 7,000 independent butchers in this country."

He said to compete effectively, small retailers had to offer something differently from supermarkets.

Mr Hawkins said it was simplistic to suggest supermarkets were all out-of-town.

"Lots of supermarkets operate smaller stores and some of us never left the High Street," he added.

He added Safeway had about 200 High Street stores, out of its 480 across the UK.

A Sainsbury's spokeswoman said: "We know customers want choice and convenience, so they want flexibility in the range of foods we offer and the types of stores we provide."

That meant shoppers had the choice to buy locally grown food in a High Street branch, she added.