Downing Street has said the Government had "no plans" for a windfall tax of the type proposed by Sir John Major.
David Cameron's official spokesman told a regular Westminster media briefing: "The Prime Minister's view on this is that this is an interesting contribution. We have no plans for this."
"What the Government is doing is legislating around forcing energy companies to put customers on their lowest tariffs and more competition in energy markets."
Asked about Sir John's concerns about people having to choose between eating and heating this winter, he said:
"There are a number of initiatives that the Government has to support vulnerable people, such as the cold weather payments.
"We have a range of ways in which support is given and those are the right ones."
Scottish Power has increased its gas and electricity bills as rifts appear in the Coalition over green energy taxes.
David Cameron has announced a review of competition in the energy market and vowed to roll back green regulations.