Supermarket chains have been slammed by political parties, trade bodies and environmental groups which believe they have too much power.

The Green Party says in its election manifesto that it will support smaller shops with planning policies that set aside 50% of retail floor space in all new developments for local businesses.

The Greens join the three major parties in their support for a supermarket code and an independent regulator for the food industry.

Tesco was a particular target after announcing a £3.4bn profit for the last financial year. The Rural Shops Alliance (RSA) said the chain had too much power in the market and urged the government to create a more level playing field.

RSA chief executive Ken Parsons said: "£3.4bn means you can afford to buy virtually any site in the country to develop a new supermarket. If you get turned down for planning permission you can afford to appeal as many times as you need, or run a store at a loss to undercut local competitors."

He asked the government to consider advice and grant schemes that would help businesses thrive.

Friends of the Earth also accused Tesco of destroying communities. Spokeswoman Helen Rimmer commended the public campaigns against Tesco and called on the next government to help small shops.

"The fightback against the Tesco takeover is building, with more than 300 community campaigns against new Tesco stores opening around the country," she said.

"The next government must do more to support small retailers and introduce new rules to rein in the bully-boy tactics of the major supermarkets."