It comes at a time when many homeowners are facing the challenge of paying higher utilities bills – such as those to dual fuel providers.
British Gas also faced criticism last October when it introduced a hike in many of the tariffs it offers to consumers.
That led to Ofgem launching an official investigation – something it could do once again following the confirmation of huge profits.
Alistair Buchanan, chief executive of the regulatory body, tells the Daily Telegraph: "If any company in generation or supply were to take advantage of rising prices the punishment meted out will be swift and appropriately ugly."
Ofgem recently announced some 70 per cent of Britons have trouble reading their bills and would like firms to make invoices clearer, the same newspaper reported.
Posted by Jim Tidy
Click here to run an energy price comparison, and see if you could be paying less for your gas and electricity.