Electricity Prices to rise. Photos of National Grid Power Lines from Sizewell Nuclear Power Station. Images taken 28/5/2011. Sizewell, Suffolk, UK.
Millions of energy customers face a 20pc increase in their utility bills this winter, just months after gas and electricity providers raised prices by more than 10pc.
Scottish Power is the first of the big six to make the move and others are expected to follow. The shock increases come at a time when turning up the thermostat will be furthest from people's minds.
From August, Scottish Power will increase the cost of its gas and electricity bills by 19pc and 10pc respectively – adding an additional £175 a year to the average bill.
Audrey Gallacher, head of energy at Consumer Focus, the statutory consumer champion, warned: "Suppliers like the comfort of the pack and, because of that, price rises often come in waves."
Energy providers have been accused of profiteering and many consumers will also be questioning the steep rises they are about to face.
The chairman of British Gas owner Centrica has warned households to brace themselves for further steep increases in gas and electricity bills, it has been reported.
Sir Roger Carr said that the wholesale cost of power has risen by more than 20% in recent weeks, making price hikes across the industry inevitable.
Last week Scottish Power, which serves 2.4 million households, announced that gas and electricity prices would rise by 19% and 10% respectively, adding £173 to the average annual dual fuel bill from August 1.
The move from Scottish Power is expected to herald a fresh wave of energy bill rises, after all the "big six" suppliers put their prices up over the winter.
Sir Roger: "Moving wholesale prices have been very material, well over 20%, in recent months.
"In those circumstances, it is just a commercial fact that those things convert into price increases.
"It's high. Nobody likes higher prices but it's passing on costs which nobody can avoid."
Sir Roger, who is also president of the Confederation of British Industry, refused to comment on future prices at Centrica.
But Centrica, which has around 16 million energy accounts, last month said the price paid by households has yet to reflect fresh wholesale price hikes, hinting that further rises were on the way.
The Bank of England has also warned it expects household energy bills to rise by 15% this year, heaping more misery on cash-strapped consumers.