For a typical household on dual fuel, that means that the average annual bill will increase by 7.3 per cent or £76.
British Gas today announced a 12.5 per cent hike in electricity prices from next month in a direct snub to the Government.
This is made up of customers on fixed deals, gas-only customers, customers on prepayment meters whose tariffs are subject to an Ofgem regulated price cap, and around 20,000 customers who receive the Warm Home Discount who will be credited £76 by British Gas to protect them from the price rise.
The FTSE 100-listed company justified the decision by saying it was the first time it had hiked prices since 2013 and British Gas was one of the last suppliers to make tariffs more expensive.
The move affects 3.1 million customers, although British Gas says a further 5.3 million customers are unaffected.
Shares rose 2.6% on the news.
In a statement, the company said it held off from the price rise a for "up to six months longer than some of our competitors".
"For example, British Gas managed to lose 377,000 United Kingdom customers in the first half of the year, despite waiting until after its rivals had increased prices before following suit".
British Gas has ended its self-imposed moratorium on raising energy prices and announced a hefty 12.5 per cent increase in electricity prices from mid-September.
The result was a severe drop in statutory profit attributable to shareholders in the first half to just GBP44.0 million from GBP1.14 billion the year before - a 96% drop.
"We're actually proposing that the Government are even bolder and instead of capping standard variable tariff, they should reform it so that it's removed altogether so that contracts that don't have any end are actually phased out and that the level playing field is created so that all suppliers pay the Government's costs", Mr Conn said.
Cushion gas is the minimum volume of gas required in an underground storage reservoir to provide the necessary pressure to deliver working gas volumes to customers.
The company said it booked net exceptional charges in the first half of 2017 amounting to GBP268.0 million and GBP176.0 million worth of losses from certain re-measurements, compared to the year before when exceptional items only totalled GBP63.0 million and re-measurements generated a GBP704.0 million net gain.
The Energy Department spokeswoman added: "We want to see rapid progress on this commitment".
With utility price rises across the board now looking more likely, we crucially need to review the key priorities across the United Kingdom before the coming winter - when 4 million households in the United Kingdom will face the brunt of fuel poverty.
The group insisted its overall electricity costs had increased by 16% since 2014.