ScottishPower has announced prices rises of 15 per cent for gas and 14 per cent for electricity for its 5.2 million customers.

Customers on the firm’s dual fuel tariff will see prices rise 14.8 per cent.

The energy provider attributed the rises – following those from Npower, EDF and British Gas last month – on annual rises in wholesale gas and coal prices of 83 per cent and 97 per cent respectively.

Willie MacDiarmid, ScottishPower director of energy retail, said: “We have worked hard to protect our customers from these increases for as long as possible and offer consistently competitive energy prices.

“Like other energy providers, we are now forced to pass on some of the higher [coal and gas] costs.”

The price rises will by offset for the firm’s most vulnerable customers through added credit to bills.

Analysis from uSwitch.com shows the average annual dual fuel bill at ScottishPower now stands at £1,100 – making now more expensive than British Gas (£1,055), EDF (£1,007), and Npower (£1,056).

Ann Robinson, director of consumer policy at uSwitch, said: “Today’s announcement will come as no surprise to consumers – a price hike was inevitable from the day that other suppliers put their prices up.

“Those looking to minimise the impact of higher energy costs on their household budget should seriously consider taking the following steps: move to dual fuel, pay by direct debit and go online.”

She added: “The question now is whether suppliers will be prepared to drop prices again if wholesale prices should fall, as they did last year, or whether the £1,000 bill is back for good.”