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Millions of households will pay even more for gas and electricity after EDF, the energy company, announced price increases of up to 22 per cent.

Other energy suppliers are expected to follow, and analysts gave a warning that another round of price increases was likely in January. EDF, which supplies more than five million people mainly in London and the South East, is putting up electricity bills by 17 per cent and gas bills by 22 per cent. An average joint bill rises by more than £200 a year (£4 a week) to £1,211.

The French-owned EDF blamed high oil prices and record wholesale gas prices for the latest increase. Since 2003, EDF gas prices have increased cumulatively by more than 130 per cent and electricity prices by more than 94 per cent.

Industry experts said that EDF may be forced to raise prices again in January. Analysts believe that the six big suppliers will have to put up tariffs by 40 per cent by the end of the year, as forward prices for the coming winter have leapt from 60p per therm in January to 93p per therm now. This time last year, forward prices for the coming winter were just 44.5p per therm.

Eva Eisenschimmel, chief operating officer of EDF Energy’s customers branch, said: “Record world oil prices have continued to drive up wholesale gas prices. Alongside unprecedented rises in wholesale coal and electricity costs, this has impacted hugely on the cost of supplying energy to our customers.

“We have been absorbing some of these costs in recent months, but we now have to pass on some of the resulting rise in wholesale costs to our customers.”

Energywatch, the consumer watchdog for the energy markets, said that the latest price increase would be a serious blow to many households.

Adam Scorer, Energywatch director of campaigns, called on the Government to investigate the link between soaring oil prices and wholesale gas prices. “The indexation of the price of these two entirely separate commodites must be explored and if the link is found to be artificial and unfair then action needs to be taken,” he said.

Ofgem, the energy markets regulator, investigated the link between oil and gas in 2004 and found that greater connections between Europe and Britain’s gas market – because of new gas pipelines – lay behind the recent linking of the prices.

It has since presented its findings to the European Commission and used them to lobby for liberalisation of Europe’s gas and electricity markets.

Analysts believe that British Gas, the biggest energy supplier with more than 16 million customer accounts, will shortly raise prices.

It is expected to wait until Centrica, its parent company, reports half-yearly results next week which are predicted to show that profits in its British Gas arm have collapsed.

Scottish and Southern, the UK’s second-biggest energy supplier, said it was under unbearable pressure to raise its prices. All six suppliers are likely to have raised their prices before the winter, when demand for gas and power is at its peak.

Yesterday EDF said that 100,000 of its poorest customers would benefit from a 15 per cent discount, after it expanded its social tariff. However, it is spending just £11 million on targeted help for vulnerable customers.

An EDF spokesman said: “There’s never a good time to announce price increase but we have seen unprecedented increases in wholesale energy costs and our tariff changes are as a result of that.”

EDF Energy’s announcement that it is to put up prices has coincided with speculation that its parent company, EDF, is very close to buying British Energy, the nuclear generator, for more than £11 billion. EDF denied that there was any link.

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