The UK’s major energy firms have been slammed over their profit margins, which have risen from £15 per customer in June to £125 ($197), according to energy regulator Ofgem.

The so-called Big Six energy companies – British Gas, EDF, EON, npower, ScottishPower and SSE – have been under fire for more than a year over their price increases and tariff complexity, and Ofgem has now pledged to force them to simplify their price structures for customers.

Tim Yeo, chairman of the government’s Energy and Climate Change Committee, attacked the profit margins as “evidence of absolutely crass behaviour by the energy companies”.

Earlier this week the new shadow energy secretary Caroline Flint called for simpler tariffs that involved “a daily standing charge at a cost per unit, like a phone bill”, while SSE’s chief executive Ian Marchant said he was working on a “radical price model” that would end tariff complexity.

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