Some nine million customers will be hit when the supplier raises gas and electricity prices by an average of 18 per cent and 16 per cent respectively from August 18.

The average dual fuel bill will rise by £190 a year to £1,219, pushing the average monthly bill to £101.58p, piling pressure on already-squeezed household incomes.

Last month, Scottish Power announced a similar hike in bills and the rest of the 'big six' suppliers are expected to follow suit in coming weeks.

The British Gas move intensified calls for a review of the energy market and will leave more households facing the choice between heating or eating.

The firm said the hike was in response to a 30 per cent increase in wholesale prices since last winter, claiming it was currently selling energy at a loss.

But Mike O'Connor, chief executive of Consumer Focus, said wholesale prices are still a third lower than their peak in 2008 yet British Gas had hiked gas and electricity prices by around 44 per cent and 21 per cent respectively in that period.

He added: "This price rise will send a shock wave across the country. The impact on customers will be severe, piling more pressure on severely stretched household budgets and pushing hundreds of thousands more households into fuel poverty."

The most recent rise means that some bills will increase by as much as 24 per cent depending on how customers pay and where they live. The minimum increase will be 12 per cent.

British Gas managing director Phil Bentley said: "We know there is never a good time to raise prices but we are buying in a global energy market and have to pay the market rate."