JEREMY CORBYN vowed yesterday to slash spiralling household bills by bringing Britain’s “Big Six” energy companies into public ownership.

The Labour leadership front runner issued the warning to bosses at the “failing cartel” as he launched his environmental manifesto at Camley Street nature reserve in London.

He promised to replace the “broken, dated and polluting energy market” with socialised gas and electricity supplies.

“I want the public ownership of the gas and the National Grid,” he said in an interview with Greenpeace to coincide with the launch.

Mr Corbyn explained that the government could renationalise the companies by purchasing the majority of shares, adding: “Does it cost? Yes. Is there a return? Yes.”

But on top of a national company, he committed Labour to supporting community owned energy if he is elected party leader next month.

The policy is inspired by Germany, where more than 180 towns get cheaper and cleaner electricity from local power grids.

That has left Germany’s biggest four energy companies with just a 5 per cent market share, compared to the 95 per cent of Britain’s Big Six.

Mr Corbyn’s manifesto also included an ambition to create 1 million jobs by investing in “modern, green, resource-efficient” energy.

He was clear that the policies were not only good for the environment, but good for the Labour Party.

In 11 marginal seats that Labour lost to the Tories in the general election, the Green vote was more than the Tory candidate’s majority, opening an opportunity for a more environmental Labour at the 2020 election.

Morley and Outwood, where the Greens polled 1,264, saw shadow chancellor Ed Balls lose by 422.

“There is an electoral dimension. We must reach out to those voters who care deeply about the environment if we are to build the electoral alliance we need,” said Mr Corbyn.

The Green Party declined to comment on the substance of Mr Corbyn’s proposals, though a spokesman did say: “We look forward to examining the green credentials of this document should it become official policy. In the meantime, Labour’s leadership contest is a matter for them.”