Around 1.5m Scots households are to see their energy bills soar by up to £693 a year after the regulator Ofgem hiked the price cap by the biggest increase yet.

Households that use a default energy tariff to buy their gas and electricity can expect a sharp increase in their bills from April 1 after the regulator lifted its energy price cap.

The sharp 54% rise, which will impact half the population, is said to be driven by a record rise in global gas prices over the last 6 months, with wholesale prices quadrupling in the last year.

From April 1, the three in four customers on default tariffs paying by direct debit will see an increase of £693 from £1,277 to £1971 while the rest who are on prepayment meters will see a rise of £708 from £1,309 to £2017.

It will affect default tariff customers who haven’t switched to a fixed deal and those who remain with their new supplier after their previous supplier exited the market.

Jonathan Brearley, chief executive of Ofgem, said: “We know this rise will be extremely worrying for many people, especially those who are struggling to make ends meet, and Ofgem will ensure energy companies support their customers in any way they can.

“The energy market has faced a huge challenge due to the unprecedented increase in global gas prices, a once in a 30-year event, and Ofgem’s role as energy regulator is to ensure that, under the price cap, energy companies can only charge a fair price based on the true cost of supplying electricity and gas.

“Ofgem is working to stabilise the market and over the longer term to diversify our sources of energy which will help protect customers from similar price shocks in the future.”

The trade association, Energy UK which has been calling on the UK government to intervene to help cut the cost of bills amid had predicted that the price cap for a typical household could rise to as much as £1,900 today.

Customer research carried out by Public First for the trade association has found that a quarter of respondents say they would not be able to afford the anticipated £50 monthly increase in their energy bills.

Energy UK says it  comes as the cost of buying gas on the wholesale market has rocketed in recent months - rising by over 500% in under a year. Much of this rise occurred since the current price cap was set.

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Energy UK say suppliers had been losing up to £400-£600 per household because they cannot charge what it currently costs to provide energy to their customers.

Citizens Advice Scotland said that the Ofgem announcement would come at the "worst possible time" as prices in the shops soar and incomes stay the same or even fall.

Ofgem's announcement was brought forward from next Monday.

But Boris Johnson is said to be poised to provide a safety net for consumers and give the green light to provide billions of pounds in state-backed loans to energy firms in return for a £200 cut in the impact of soaring energy prices on household bills.

Chancellor Rishi Sunak is expected to lead a press conference at 5pm to set out his plans to help people cope with rising energy costs.

The cap came in as energy wholesale prices continued to climb and was put in place to stop companies from immediately passing those costs on to their customer.

The price cap is updated twice a year and tracks wholesale energy and other costs.

Its aim was to stop energy companies from making excessive profits, ensuring customers pay no more than a fair price for their energy.

The cap allows energy companies to pass on all reasonable costs to customers, including increases in the cost of buying gas.

Ofgem said since the price cap was last updated in August, the level does not reflect the "unprecedented record rise" in gas prices which has since taken place.

Under the price cap mechanism, energy companies will be allowed to pass on these higher costs from April when the new level takes effect.

Ofgem says this is because energy companies cannot afford to supply electricity and gas to their customers for less than they have paid for it.

Over the last year, 29 energy companies have exited the market or been put in special administration in the wake of soaring global gas prices, affecting around 4.3 million domestic customers.

The chief executive Energy UK has called on the Government to act with the industry to deal with the “once-in-a-generation international gas price crisis”.

Emma Pinchbeck said: “The energy industry has already put up millions of additional pounds of extra support through this winter.

“We could see the prices rising from September so we knew it would be really tough for people.

“The point is that this is record-breaking levels of gas prices and what we’ve been doing is trying to get Government to act with us as other governments across Europe have been.”

She noted that with gas prices up “something like 900% since the start of last year, most European governments have put in place additional support both for customers and businesses”.

She went on to say: “Of course it’s right that the industry looks after its customers, it’s a really shocking price rise for many people.

"Our point is, I don’t think that the industry can do this alone and particularly not with the state of our retail sector in the UK”.

One debt management charity has said they have been been “inundated” with inquiries from people choosing between “heating and eating”.

Sylvia Simpson, project director at Leeds charity Money Buddies said the the charity is even seeing people with incomes struggling to pay their bills.

She said: “We see it in clients coming to us every day, we are inundated with people coming to see us.

“We had one recently where she was choosing between heating her home or eating a warm microwave meal as she turned the fire off to turn the microwave on."