The 8.2% rise in SSE bills is "disappointing" but "for the company to justify", an energy minister has said.
Conservative Michael Fallon hoped "customers would look very carefully" at tariffs and think of switching if bills became unmanageable.
However, he hinted there would be no Government intervention and instead wanted to create more competition under the 2013 Energy Bill, which is already making its way through Parliament.
SSE, which has around 10 million customer accounts, blamed the increased cost of buying and delivering wholesale energy as well as Government levies collected through bills.
It said the latest increase, which is three times the rate of inflation, would come into effect from November 15.
The company, which trades as Southern Electric, Swalec and Scottish Hydro, said the hike equated to an average £2 a week for a typical dual fuel customer.
Will Morris, SSE retail managing director, said the firm was "sorry" to have to raise its prices:
We're sorry we have to do this.
We've done as much as we could to keep prices down, but the reality is that buying wholesale energy in global markets, delivering it to customers' homes, and government-imposed levies collected through bills - endorsed by all the major parties - all cost more than they did last year. Eighty five per cent of a typical energy bill is made up of costs outside our direct control and these costs have increased.
So far this year we have made a loss from supplying energy as a result of the higher costs we have been facing and continue to face. We understand and regret that this will add to the pressures on household budgets, but there's a lot we can do to help.
Rising unit prices do not have to mean rising bills and there remains huge potential for customers to save money by improving further their energy efficiency.
Energy company SSE said household electricity and gas tariffs are to increase by an average of 8.2% from November 15.