Scottish Power is to raise the cost of gas by 19% and the cost of electricity by 10%.

The utility firm said the increase, which would affect 2.4 million households in the UK, would come into effect from 1 August.

Affected customers will see an average daily rise to a dual fuel energy bill of 48p per day.

The company said the move reflected sustained increases in the wholesale energy market.

Scottish Power is the first to announce a new wave of price increases. Average gas bills will go up by 19% at the start of August, electricity by 10%. The scale of the increase has taken some in the industry by surprise.

Adam Scorer from Consumer Focus commented "If this is replicated across the market, about 400,000 consumers are going to find themselves in fuel poverty, are not going to have enough money for other essentials and will have to start making those really invidious choices about whether you put food on the table or whether you keep your home warm. That's the consequence."

The wholesale price of gas has been going up since the end of last year, partly as a result of the higher cost of oil and the continuing unrest in the Middle East hasn't helped.

In a statement Scottish Power said: "We understand times are difficult for many people and we have done what we can to absorb these additional costs for as long as possible to minimise the impact on our customers."

Today's price hike will affect 2.4 million Scottish Power customers across the country. On one estimate, it will add £180 to the cost of an annual average dual fuel bill. We're likely to find out what the other five big energy suppliers are planning in the coming weeks and months.

Energy regulator Ofgem will be watching these events closely. They have already accused suppliers of being more eager to raise bills when the price goes up than to reduce them when costs fall. Higher energy bills are one big reason why inflation is expected to hit 5% later this year. Today we had the first real taste of what's to come.