MILLIONS of British Gas customers face a 14.2% rise in their bills - the third increase since January last year.
Parent firm Centrica said soaring oil prices and dwindling North Sea gas reserves had forced it to follow the lead of rivals Powergen and EDF Energy.
It also said British Gas profits would be significantly reduced in the second half of the financial year as it faced up to volatility in the wholesale energy markets.
The price rise, from September 19, will hit many hundreds of Huddersfield householders.
A Centrica spokesman said there would be no further increases in bills this year after the move, which follows a 5.9% rise in January last year and a 12.4% increase eight months later.
The new rise means a family in a typical three-bedroomed semi will see their annual gas bill rise from £405 to £462, while their electricity will now cost £39 more a year at £307.
The move will affect 16.2m customers whose energy is supplied by British Gas, although an extra 1m are protected by their decision to sign up to its price protection plan.
That allows customers to cap the price they pay for gas and electricity until 2007.
British Gas said it was offering households who pay for "dual fuel" the chance to fix their energy prices until 2010 at no extra cost.
Karl Brookes, of consumer organisation energywatch, said British Gas was now the most expensive supplier of gas.
He urged customers to switch from British Gas, saying they could save at least £80 a year.
British Gas said the latest rise in bills would not fully cover the rising cost of wholesale gas and electricity, which is 50% and 61% higher than a year ago respectively.
It is also taking action to protect the poor and elderly who are struggling with their bills by offering a rebate of up to £60 to 250,000 of its customers.
Managing director Mark Clare said: "We are no longer an energy island.
"Spiralling world oil prices are now having an unprecedented impact on the cost of gas as the UK is now dependent on imports."
