The Big Six energy suppliers have been accused of harbouring vested interests and not providing the best gas and electricity prices for their customers.
Ed Miliband made the remarks in his leader's speech to the Labour party conference this week - and they were echoed by environmental lobby group Friends of the Earth.
Craig Bennett, the organisation's director of policy and campaigns, said Mr Miliband was right to call for an end to the dominance of the major suppliers in the energy market.
He said: "The government must allow smaller players into the market and support businesses to provide our homes with long-term affordable, clean energy."
Adding: "The Labour leader should step up his opposition to feed-in tariff cuts - this funding is vital for encouraging households, businesses and communities to create their own green power."
Meanwhile, consumers who want to do their bit for the environment could look online for green energy tariffs and make the switch.
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