Gas and electricity provider npower has seen its profits for the first quarter of 2012 fall compared to the same time last year.
The firm saw an operating profit of £244 million for the three-month period, a fall of 31 per cent from 2011's figures.
It blamed this on reduced consumption by domestic energy users and smaller margins in its power generation sector.
Chief executive of the company Volker Beckers said: "During 2011, npower customers paid just over £20 a week on average for all their gas and electricity needs, with about a £1 a week of that as profit to npower."
He added the firm has invested more into infrastructure than any other firm and now has the largest installed renewable energy generation capacity of any provider in the UK.
The announcement comes as a forward-looking statement from British Gas warned prices for gas and electricity are set to rise in the coming months.
Make sure you're not paying too much for your energy - compare gas and electricity prices now at energyhelpline.com or call 0800 074 0745