Labour leader Ed Miliband is to make a fresh attempt to reach out to business with a promise to protect small firms from “unfair” treatment at the hands of the energy companies.

In a speech today to the Federation of Small Businesses (FSB) in Manchester, he will say that a Labour government would reform the energy market to ensure small firms were given the same legal protections as householders.

These would include establishing a new energy regulator with powers to suppliers from rolling firms on to more expensive tariffs without their consent or hitting them with “crippling” back-bills for periods of longer than a year.

“It is unacceptable that companies like yours do not have even basic protections that are available to households under the law from unfair energy contracts,” he will say.

Labour would also give business organisations like the FSB new legal rights to take cases - such as late payment by firms or government departments - to court on behalf of their members.

It would also invite the FSB to join Which? and Citizens Advice in helping to set the agenda for the Competition and Markets Authority’s investigations to ensure markets were working properly in the interests of consumers and businesses.

“Since the turn of the century, the number of people working for themselves has increased by over one million,” he will say.

“Small businesses are now the bedrock of our economy.

“The Labour Party has always stood up for working people.

“If we are going to do that in the future, the party I lead will recognise that millions of working people are working for themselves.”