Households are braced for a fresh round of energy bill rises after Scottish & Southern Energy raised its gas prices by 9.4 per cent.

SSE, which owns Southern Electric, Scottish Hydro and Swalec, blamed the price rise, which will come into effect on December 1, on a 25 per cent increase in the wholesale price of gas this year.

It means the average annual household gas bill for an SSE customer will increase by £5.60 a month to £782. A dual fuel customer's annual bill will rise to £1,226 from £1,159 a year ago.

The timing of the rise could hardly be worse for consumers as it will come at the start of winter when gas consumption soars, and just weeks before Christmas and a planned rise in VAT to 20 per cent.

Mark Todd, director of Energy Helpline, said SSE was the first major supplier to increase gas prices for two years but others were likely to follow suit.

"This is a grim Christmas present for millions of customers before what's predicted to be a very harsh winter," he said.

"We expect there to be a response from the other suppliers, and it's likely there will be at least a few that move before Christmas. UK consumers are in the last chance saloon for cheap energy deals and must act now if they want to keep their costs down."

He also warned the price risies might not be restricted to gas after EDF became the first major player to put electricity prices up, when it implemented a 2.6 per cent rise on October 1.

Watchdog Consumer Focus said wholesale gas prices are still 40 per cent below their peak in 2008, whereas SSE's prices ware just two per cent below their 2008 peak.

Audrey Gallacher, head of energy at Consumer Focus, said: "We are worried this could be the start of some serious bad news for all consumers.