Powergen has announced that its customers energy bills will rise by as much as 18.4 per cent starting from Monday, 21 August.
Electricity customers face a rise of 9.7 per cent while gas customers will pay 18.4 per cent more.
The energy giant blamed the latest hike on the increasing cost of wholesale energy, which it says has risen by 87 per cent since the beginning of 2005.
In March, Powergen – which has 8.5 million UK customers – raised the price of gas by 24.4 per cent and electricity by 18.4 per cent.
Nick Horler, Managing Director of Powergen Retail, said: ‘We take today’s announcement very seriously and have fully considered its impact on our customers.
‘Despite this increase, for the average customer, we are still over 10 per cent cheaper than British Gas and we remain fully committed to working with our customers to help them reduce their consumption and lessen their impact on the environment.
‘We also continue to invest billions of pounds in the UK to help ensure the lights stay on and homes are warm.’
Every major energy supplier in the UK has now increased prices twice this year.
British Gas has already announced its customers face a 12.4 per cent increase in gas bills and 9.4 per cent hike in electricity bills from 4 September, while EDF Energy, Scottish Power, Npower and Scottish & Southern Energy have also announced increases.
Consumer group Energywatch said the average Powergen gas bill was now £644 a year – up 107.5 per cent since 2003 – while the average electricity bill was £333 – up 62.1 per cent.
Energywatch Director of Campaigns Adam Scorer said: ‘With millions in fuel poverty, government and industry must come up with an effective strategy to protect those vulnerable customers most in need.’
Which? runs its own impartial energy price comparison site – Switch with Which? – where you can check which supplier offers the best deal for your gas and electricity.
People can save, on average, £160 by switching suppliers – with the biggest savings likely to be made by those who haven’t switched before.