The energy firm has blamed increased costs, including a 34% increase in the cost of delivering government schemes, like green energy efficiency programmes, for this energy price rise.

It is estimated that this price hike will affect around 2.3m households across the UK, as a result a monthly Direct Debit customer will see an increase of 8.7%, with a new average annual Dual Fuel bill of £1,271.

Clare Francis consumer expert at MoneySupermarket.com said: “Following announcements late last week from British Gas and npower, Scottish Power has unsurprisingly followed suit, announcing an increase to gas and electricity prices by an average of seven per cent, effective from December 3, 2012.

“Energy customers are being hit hard from all sides, just as the cold weather approaches. For anyone paying their energy provider’s standard prices, it’ll be an expensive winter if they don’t take action.

“Don’t delay, switch now onto a fixed online tariff – not only will you beat the price hikes, you’ll also protect yourself in case of further increases next year.”

Scottish Power is the 4th supplier to announce a hike in energy prices following SSE’s announcement in August that they would be rising gas and electricity prices by 9% with effect from today and announcements from British Gas and nPower last Friday.

Francis added: “Surprisingly, Scottish Power has staggered increases to customers depending on the method of payment. Worst affected are those on Scottish Power’s standard tariff who pay monthly by direct debit and customers with pre-payment meters.

“After being encouraged for years to switch to a monthly direct debit option, it’s a slap in the face to penalise those who have done so by hitting them with the biggest price increase.”

Kate Rose, head of energy at confused.com, said: “Three easy steps customers can take to lower their energy costs and make sure they are paying as little as possible are; getting your gas and electricity supplied by the same supplier (dual fuel), paying by direct debit and switching to online account management.

“We also suggest customers look at opting for a fixed price or capped tariff which can offer price security.”

E.ON and EDF Energy are the two remaining ‘Big Six’ energy providers that have not announced price rises. However industry experts predict price increase announcements from the remaining two providers.