EDF Energy has raised its prices by almost a fifth from today without warning, hitting customers with double-digit price increases in what is expected to be an industry-wide rush to put up gas and electricity bills.

The French-owned electricity giant's five million customers will see an immediate 17 per cent increase in electricity bills and a 22 per cent increase in gas, which it blamed on wholesale prices that have risen by 70 per cent since the beginning of the year.

Most customers will have to pay almost £4 a week or £200 a year more for their energy.

Eva Eisenschimmel, chief operating officer of EDF Energy 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. While the rise in wholesale prices is out of our control, we have been doing everything possible to keep our own costs in check."

The other five main energy suppliers are quickly expected to follow suit, with most expected to raise their prices before the end of August. Yesterday Scottish and Southern, the UK's second biggest energy supplier, said it was under unbearable pressure to raise its prices and would have to bow to that pressure soon.

British Gas, the UK's biggest supplier with 16 million customers, is expected to reveal a slump in profits at its residential supply business when it reports interim results next week. British Gas is also widely expected to put up prices in the next few weeks after it released a report last week that said that with oil at about $140 a barrel, the price of gas for an average household could hit £1,000 a year over the next two years.

EDF Energy moved quickly to try and minimise the impact on its most vulnerable customers, saying that 100,000 of its most-in-need 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.

A spokesman for EDF Energy said that it had been making preparations to raise prices for several weeks and the timing of its the decision, taken last night, had been dictated by business matters.

"There's never a good time to announce price increase but we have seen unprecedented increases in wholesale energy costs and are tariff changes are as a result of that," the spokesman said.

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 between the British Energy deal and its tariff increases. "Our planned investment in new nuclear has to be seen as part of a long-term strategy and part of our responsiblities to safeguarding future energy supplies," he said.

Wholesale energy prices have increased by 70 per cent for coal, 63 per cent for gas and 47 per cent for electricity since EDF Energy last increased its prices in January, EDF said.

According to industry sources gas prices for the winter are double what they were last winter, with winter gas trading at 94p a therm, compared with 48p a therm last year.