Householders face price rises of up to 15% for gas and electricity, with Npower preparing to lead the way with an increase in double figures today.

Npower has 90,000 customers in Scotland out of its four million UK-wide but other companies are expected to follow suit on the back of energy wholesale prices which have already triggered increases in tracker tariffs - which link wholesale fuel costs to domestic prices.

Tim Wolfenden, who is head of home services at, said: "Price rises have been on the horizon for some time.

"Ever since British Gas and Npower announced price increases on their market trackers and Npower followed this up with a price hike on its online plan, it has been clear that prices are going to be heading north again, with the smart money on a 15% rise.

He warned Npower's decision to increase standard rates by between 10 and 15% will "give competitors the green light" to follow suit.

It is thought wholesale prices in the UK have also been driven higher as European firms turn for supplies to the more-liberalised UK market as a cheaper alternative.

Npower, which is owned by German company RWE, has already increased its online tariff for new customers, upping bills by 17% the week before Christmas, but the latest move, accompanying the winter's first serious snowfalls in lowland areas, marks the first by an energy supplier to increase standard rates after last spring's price cuts.

British Gas parent company Centrica last month announced increases to its market tracker price, increasing bills by 13% for gas and 15% for electricity. It also warned less than two weeks later that wholesale prices left the energy industry facing a "difficult environment" in 2008, signalling that prices were set to rise across the board.

A drop in wholesale energy prices in 2006 and early 2007 had enabled suppliers to cut bills, with British Gas becoming the first major UK energy firm to announce decreases.

Npower dropped its prices at the end of April 2007 and, before today's expected price increases, has been the fourth-cheapest of the six biggest UK energy suppliers, according to

Its average standard dual fuel bill stands at £908 a year, the price comparison website said.

But today's announced increases could see the group become the second most expensive provider, behind Scottish Power, which charges on average £958 a year for standard dual fuel bills.

Its cuts in April last year saw the group trim prices by 16% for gas and on average by 3% for electricity.

Independent gas and electricity consumer watchdog energywatch condemned Npower's news. Spokesman Karl Brookes said: "Consumers are always being softened up with talk of unavoidable' price rises.

"The wholesale price for gas has risen, it's true, but all suppliers can decide to absorb more of that themselves rather than pass all the risk on to consumers."

Mr Brookes added: "In the last year wholesale gas prices have fallen by 50% and, while the industry enjoyed the respite, they were in no hurry to share the benefits with consumers.

"Suppliers waited until spring last year to pass on miserly reductions to their customers of an average 15% off gas bills and an average of 4.9% off electricity bills."

There was further gloom on the energy front yesterday, with the rise in crude oil prices expected to work through to petrol stations.

The price of oil set a new record of $100.09 (US ) a barrel as figures revealed worse-than-expected US oil stocks. This quashed hopes that the $100 high reached the day before had been a fluke.

In the UK, drivers had to pay an average of 103.3p for a litre of petrol yesterday, beating the previous record of 102.92p set on Boxing Day.

It meant that the cost of filling a typical 50-litre tank was £7.36 more than a year ago.

The only hope appears to be that costs may ease back this year as the world's economy slows, dampening demand. This could induce the Opec oil cartel to consider raising production levels next month.