CONSUMER watchdogs have hit out at the latest round of energy price hikes due to affect more than one million Scottish households, branding them a "bitter blow" for cash-strapped consumers.

Energy giant British Gas – which operates subsidiary Scottish Gas – and npower have both announced tariff increases just as the country braces itself for another harsh winter.

British Gas will increase its prices by 6%, an average of £76 per year, while npower will increase its gas prices by 8.8% and electricity by 9.1%, an average of £109 per year.

Deputy First Minister Nicola Sturgeon has condemned the move along with Scotland's consumer groups, who have warned householders may buckle under the pressure of the price hikes and be afraid to turn on the heating.

Trisha McAuley, deputy director of Consumer Focus Scotland, said "These price rises will leave customers in Scotland even more worried about the cost of heating their homes this winter. They will see average annual energy bills rocket even further.

"These and other expected price rises will tip even more households into fuel poverty, with over one million households in Scotland already struggling to afford their bills."

British Gas will increase its prices from November 16, taking the average bill for a dual-fuel customer to £1336 per year. npower prices will increase on November 26 and take the average bill to £1322.

Fellow "big six" fuel company SSE has already announced plans for a 9% fuel hike, which comes into effect on Monday.

Other major companies are expected to follow suit, with only E.ON pledging to hold its prices for the rest of this year.

Ms Sturgeon said the rises would have an "extremely damaging effect on the finance of Scottish households" and that she wanted to meet all energy companies as soon as possible to discuss them. She added: "For every 5% price increase in energy prices, 46,000 households are pushed into fuel poverty. Not only is this completely unacceptable in an energy-rich country like Scotland, it also risks undoing the good work the Scottish Government is doing to tackle fuel poverty."

She said the UK Government required to take a firmer stance with energy companies, with a need for regulator Ofgem to publish and implement their proposals to protect consumers as a matter of urgency.

Ann Robinson, director of consumer policy at comparison website uSwitch.com, added: "This is a bitter blow for consumers and comes just ahead of winter, when the impact on bills will be even more acute.

British Gas claimed the company was facing rising wholesale prices and higher costs to upgrade the national grid. Its managing director, Phil Bentley, said: "We know that household budgets are under pressure and this £1.50 per week rise will be unwelcome. However, we simply cannot ignore the rising costs that are largely outside our control, but which make up most of the bill.

"We need an energy efficiency culture in Britain today; rising prices don't have to mean rising bills. We are offering a huge amount of help to customers to help them cut the amount of energy they use and keep their bills under control."

He added that the firm's margins after tax in 2012 will only be 5p in the pound even after the increase – a similar level to last year.

Paul Massara, chief commercial officer for npower, said: "There is never a good time to increase energy bills, particularly when so many people are working hard to make ends meet. But the costs of new statutory schemes, increases in distribution charges and the price of gas for the coming winter are all being driven up by external factors, for example government policy."