As a result, the average British Gas customer will see their bills increase by £80 - taking their annual bill up from £1,238 to £1,318.
Npower has followed suit and revealed that it will increase the prices of gas and electricity by an average of 8.8% and 9.1% respectively from 26 November.
The two energy giants are the second and third suppliers of the 'Big Six' to announce a price hike after SSE revealed last month that it was upping its electricity and gas prices by 9% on 15 October.
Sadly, the other suppliers are expected to follow.
Scott Byrom, energy expert at moneysupermarket.com, says "there is little doubt the rest of the UK's Big Six energy providers will follow suit, leaving E.ON the only energy provider that has pledged not to increase prices during 2012".
British Gas blames its decision to increase prices on rising wholesale prices, and the costs involved in upgrading the national grid, and delivering the government's clean energy policies. Npower is also citing the government's energy policies as one of the reasons it is now upping prices.
Households under pressure
Phil Bentley, managing director of British Gas, says: "We know that household budgets are under pressure and this £1.50 per week rise will be unwelcome. However, we simply cannot ignore the rising costs that are largely outside our control, but which make up most of the bill.
"Britain's North Sea gas supplies are running out, and British Gas has to pay the going rate for gas in a competitive global marketplace. Furthermore, the investment needed to maintain and upgrade the national grid to deliver energy to our customers' homes, and the costs of the government's policies for a clean, energy efficient Britain are all going up."
However, industry experts have slammed both energy giants' for increasing prices.
Mark Pearson, chairman of myvouchercodes.co.uk, says these price rises "cannot be tolerated".
He says: "Yet another blow for the great British public struggling to keep afloat, with purse strings already tighter than ever before."
He adds that these price hikes "could bring some families to breaking point financially" and warns that "families across the country are going to struggle to make ends meet just to keep warm this winter".
Paul Crayston, spokesperson for National Debtline, says the free helpline receives a call every six minutes about energy arrears.
He says: "So far this year, 16% of people calling National Debtline have energy arrears - a big record. Despite the consecutive rises in calls on energy arrears since 2004, we expect 2012 to represent the biggest year on year jump in energy debt calls – both in terms of total calls and in terms of proportion of calls."
In total, National Debtline took 2,403 calls from people with energy arrears last month.
How to avoid price hikes
The best ways to keep your energy bills low is but switching to a better deal.
Mark Todd, director of price comparison website energyhelpline.com, says "loyalty really doesn't pay". "In today's free energy market the only way to keep down your bills is to be savvy and switch," he says.
Whether or not you're a British Gas, Npower or SEE customer, if you are worried about price hikes you should consider opting for a fixed energy tariff. This will give you the peace of mind that your bills will stay the same – sometimes for nearly two years - and you don't have to worry about your bills rising unexpectedly.
Todd says: "A typical British Gas customer could switch to a fixed rate today and save £1,265 a year. In doing so they will also guarantee themselves lower bills through the next two winters. It's a no brainer.
Some of the most competitive fixed deals have been withdrawn in recent weeks but you can still bag a good deal. However, experts warn that consumers must act quickly as the cost of fixed-price plans are creeping up.