ENERGY bills for Britain’s hard-pressed families will be capped under a future Conservative government – saving them an estimated £100 a year.

The voter-friendly move echoes a similar policy promoted by Ed Miliband, the former Labour leader, in 2013 and comes as Jeremy Corbyn launches his party’s election campaign in Manchester.

In recent months, five of the so-called Big Six energy companies have announced price rises on their standard variable tariffs used by 17 million households. Some increases have been by almost 10 per cent.

The energy companies have blamed the hikes on changes to wholesale prices as well as the cost of UK Government policies such as installing “smart meters” in homes to give consumers more information about their gas and electricity use.

A UK Government-backed investigation found families were paying around £1.4 billion more a year than they needed to. Last year Ofgem, the independent industry regulator, said the difference between the best and the worst deals on the market was as much as £300.

Tory HQ said that more than half of British households were on “poor value” energy deals. It noted how prices had risen more than 150 per cent during the last 15 years with ordinary families finding more and more of their take-home pay going on energy bills.

Last October at the Conservative Party conference, Theresa May gave notice that she was planning to take action on consumers’ high energy bills.

According to uSwitch, the price comparison website, since then the Big Six have stopped trying to match or better the cheapest deals on the market.

Under the Tory plan, the energy price cap would be set by Ofgem, building on the cap on prices for customers with pre-payment meters, which was introduced in April.

Greg Clark, the Business, Energy and Industrial Strategy Secretary, said: “Under Theresa May’s strong and stable leadership, we will act on our commitment to intervene when the energy market fails to treat people in a fair and reasonable manner.

“A recent investigation found that families are paying £1.4bn more than they should in energy bills and in the last few months five of the largest energy suppliers have announced increases to their already poor value standard tariffs. This clearly isn’t fair and reasonable and we are going to put it right,” he declared.

Mr Clark added: “This is the difference that strong leadership under Theresa May can make for ordinary working families. The alternative at this election is a weak and floundering Jeremy Corbyn propped up by other parties, risking our economy and less money in the pocket of families already struggling to pay their bills.”

Sensing the announcement was imminent, Centrica, which owns British Gas, hit out at the prospect of market manipulation by government.

Iain Conn, the company’s Chief Executive, said there were “some at the heart of the government, who just don’t believe in free markets”.

He added: “Centrica does not believe in any form of price regulation. Evidence from other countries would suggest this will lead to reduced competition and choice and potentially higher average prices.”

Lawrence Slade, Chief Executive of lobby group Energy UK, has also come out against any price cap, saying it “potentially puts at risk the billions in investment and jobs needed to renew our energy system”.