Ofgem must be stricter in cracking down on anti-competitive practices in the energy sector, according to a panel of MPs.
The so-called 'big six' energy companies should be required to publish how much gas and electricity they buy and sell to each other, the energy and climate change committee suggested in a report published today.
"Even before the recent reports of wholesale price-fixing, we were extremely concerned about the lack of transparency around wholesale prices and suppliers' trading arrangements," committee chair Tim Yeo said.
"These allegations have reinforced the need for far more transparency. We are sufficiently concerned about this whole issue of profits and pricing to want to revisit it in more detail in the near future."
MPs suggested Ofgem should publish an annual report including the profits of the energy companies.
Customers who are more likely to stick with an energy company may be getting exploited in order to subsidise winning over more savvy customers who are more likely to switch.
The report says it should be easier for people to compare tariffs between energy companies in order make the market more competitive.
"Trust in energy companies is at rock bottom and consumers don't have the right information to hand to make informed choices about where they get their energy," Yeo added.
"Most consumers simply don't know how to interpret their energy bills and this puts them off attempting to switch suppliers."
In October the prime minister seemed to cause confusion when he suggested the government would force energy companies to offer the lowest tariffs available, without appearing to have told the energy minister he was going to make the announcement.
But the policy was finally agreed by the coalition and is expected to form part of the upcoming energy bill.