Consumers are bracing themselves after Scottish Power announced a hike in its prices, with other suppliers expected to follow suit.
It said that its gas tarrifs are to rise 19% from the beginning of August, with electricity set to rise 10% from the same date. The increases are expected to add £173 to the average annual dual fuel bill.
Consumer Focus claimed the hikes will undermine public trust in the energy companies. Audrey Gallacher, the watchdog's head of energy, said: 'Companies have been softening customers up for price rises for months but customers will be shocked at the scale of this rise.'
Raymond Jack, retail director for Scottish Power UK, said: 'We understand times are difficult for many people, and we have done what we can to absorb these additional costs for as long as possible to minimise the impact on our customers.'