Theresa May is set to announce a cap on rip-off energy bills within weeks – as EDF’s tariffs soar for the second time in only a few months. The French firm raised electricity costs by 8.4 per cent last month – but it sparked fury again yesterday with the news it will push through a second increase of 9 per cent in June. The combined rises will add close to £100 to annual bills, affecting millions of households.

But the Daily Mail understands the Government is working on a scheme to protect families which will include a cap, after pressure from MPs and campaigners to step in. The Prime Minister’s spokesman said: ‘We are concerned by the planned increases. We are committed to getting the best possible deal for households and expect energy companies to treat their customers fairly. Wherever markets are not working for consumers, this Government is prepared to act.”

The energy department, BEIS, went further, saying measures to tackle ‘unacceptable’ increases will be announced shortly.

EDF Energy, which is majority-owned by the French government, blamed the price increase on rises in wholesale costs, according to The Daily Mail. But it also blamed the UK government for imposing levies on the industry to fund a move to green energy and help poorer households with discounts.