The energy price cap is the maximum amount energy suppliers can charge for each unit of energy for those on a standard variable tariff.
Ed Miliband has urged energy watchdog Ofgem to crack down on soaring costs as forecasts show the typical energy bill could soon rise by over £100 a year.
Large energy firms such as British Gas, E.On and EDF predict the price cap will increase by between five and seven per cent.
The energy regulator will announce its energy price cap for April to March on 25 February.
Mr Miliband, the energy secretary, has now written an urgent letter to Ofgem, asking the regulator to move faster to protect consumers against coming price rises.
