It is estimated that the change will effect 9 million households with the average dual fuel customer paying an extra £190 a year. The company blamed the increase on the rising wholesale cost of gas which has gone up by 30% since last winter.
In February British Gas announced a 24% increase in operating profits following swiftly behind the announcement of another 7% rise in energy bills, blaming, again, the rise in wholesale prices.
Blaming the increases on wholesale prices will be received with scepticism by consumers as prices are currently around a third lower than their peak in 2008.
In June Scottish Power became the first big-six energy supplier to raise their prices with increases of 19% for gas and 10% for electricity, these increases will take effect in August.
Consumers will now be waiting to see if the rest of the big-six will follow suit. Scottish Southern last increased prices in December 2010, Npower in January 2011, E.On in February 2011 and EDF in March 2011.
These increases will be another blow to already beleaguered families struggling with the rising cost of living.