By Leo Stevens
Energy giant Centrica could have prompted a row over energy bills by revealing that its British Gas residential arm made record profits of £742 million last year.
The UK's biggest gas supplier, which added 267,000 customers in 2010, reported the 24 per cent rise in profits just a few months after the company increased energy bills by 7 per cent.
Around half of British Gas's 16 million customers were affected by the price rise on December 10, increasing the average customer's dual-fuel bill from £1,157 to £1,239.
The rise came as customers were forced to use their heating more frequently as the coldest weather in 100 years swept the country at the end of last year.
Energy watchdog Ofgem is leading an investigation into the energy giants' balance sheets after discovering average profit margins had increased as companies claimed they had no choice but to raise their prices.
Ofgem found average margins on a standard dual-fuel tariff rose to £90 in November, from £65 in September.
But Centrica also claims British Gas prices were 0.5 per cent lower at the end of 2010 than at the start of the year after the supplier cut bills by 7 per cent in February.
Mike O'Connor, chief executive of watchdog Consumer Focus, said: "We need successful energy companies but consumers may look at today's profits and at recent price rises and question how one justifies the other."