A committee of MPs is to investigate whether consumers are paying too much for gas and electricity.
The big four energy companies recently announced recent price hikes
The Business, Enterprise and Regulatory Reform (Berr) select committee will examine if there is enough competition between the big energy suppliers.
The move came after four of the biggest energy providers recently announced double-digit increases in fuel prices.
The committee will accept written evidence from interested parties before 1 April.
The chairman of the committee, Peter Luff MP, said: "The continuing controversy over energy prices is an issue that demands to be addressed.
"It is a complex but vital question and one that affects everyone in the country, individual consumers and households, small businesses and major energy users alike."
Consumer group Energywatch has welcomed the move.
Campaigns director Adam Scorer said: "Energywatch has long voiced concerns that there are serious problems in the way the energy markets works, or rather doesn't work.
"Consumers need this inquiry to provide some clear thinking about how this market lets consumers down and what needs to be done to fix it."
A recent investigation by industry regulator Ofgem found no evidence of collusion by energy firms when setting energy prices.