Energy company to raise prices next week

The company said the charges would come into effect next Thursday and add about 54 to the average annual dual fuel energy bill.

Scottish Power's announcement follows a move last Friday by British Gas to increase gas and electricity tariffs by an average of 7 per cent.

Independent consumer watchdog Consumer Focus said the increase would "heap yet more fuel on to the fire of distrust that consumers feel towards energy suppliers".

Audrey Gallacher, head of energy at Consumer Focus, added: "Energy firms need to give answers on why customer prices have been cut by less than 10 per cent when wholesale costs have been so low for so long, yet suppliers are quick to hike prices as soon as wholesale costs start to creep up."

Scottish Power, which is owned by Spanish group Iberdrola, said its decision came after wholesale prices rose by 26 per cent per dual fuel customer since March, when it reduced prices.

But Consumer Focus said wholesale prices are still around half what they were at their peak in 2008, despite increases over the summer.

Scottish Power was the last of the "big six" to reduce gas tariffs earlier this year after sharp falls in wholesale markets.

They are the third energy group to raise prices after British Gas last week and Scottish & Southern Energy (SSE) at the end of last month. SSE said it would put up its gas prices by 9 per cent from December 1.

EDF Energy has guaranteed to freeze standard gas and electricity prices for residential customers at their current levels until at least the start of March 2011.

Consumer Focus said the increase would make Scottish Power the most expensive major provider for dual fuel customers who pay when they receive bills and the third dearest for monthly direct debit customers.