E.on, one of Britain's 'Big Six' energy companies, has revealed that UK customers could face another hike in household bills despite the group unveiling increased gas and electricity prices one day after the Autumn Statement.
According to a statement by E.on's chief executive officer Johannes Teyssen, the group thinks that it is likely that there will be further price rises over the next 18 months.
Last week, E.on said in a company statement that it will increase retail energy prices for British customers by an average 3.7% from 18 January 2014.
E.on is a member of Britain's 'Big Six' energy providers which together account for 99% of the country's supply. It was the last of the six firms to release plans for retail price tariffs.
In September, opposition leader Ed Miliband pledged to freeze energy prices until 2017, if the Labour Party wins the general election in two years.
Meanwhile, a number of the UK's 'Big Six' energy companies stated an intention to cut household bills or not raise prices until 2015.
Npower said it would not raise prices any more until spring 2015, unless wholesale costs go up, and EDF promised to adhere to the same pledge.
SSE and Centrica have said they will also pass on cost reductions.
British Gas said it was dropping household gas and electricity prices by an average of 3.2% and that these price reductions would take effect from 1 January.
Centrica, British Gas' parent company, said: "This price cut is based on the assumption that the government's proposed changes will be implemented in full."
SSE said it would cut household bills by 4% this winter.