MPs are to investigate energy price comparison websites following concerns about how they operate.
The Energy and Climate Change Committee said it will examine the role of the websites, transparency of commission received for different energy plans and the level of consumer trust they hold.
It will also look at arrangements for oversight of the websites, for example through the "Confidence Code", a code of practice that governs independent energy price comparison sites.
It said such websites played an important role in helping consumers switch energy supplier by providing comparisons of different energy plans.
But it said in recent months "concerns had been raised about the way in which these websites operate".
The committee asked for written evidence to be submitted by January 14.
Will Hodson, co-founder of The Big Deal website, which was set up last year to help consumers find cheaper energy deals, said: "It's time to clamp down on kickback culture in price comparison.
"For too long, these self-styled 'consumer champions' have taken liberties with a trusting public.
"This investigation is vitally needed and should lead to a more transparent, more competitive energy retail market."
A spokesman for the uSwitch.com comparison website said: "We welcome the committee's inquiry and believe it will provide an opportunity to recognise the important role that price comparison sites play in making the energy market work for consumers.
"We are fully accredited under Ofgem's Confidence Code, which means that consumers can compare tariffs in a fair, independent and unbiased way. We are actively working with Ofgem to update the Code so it continues to provide protection and assurance to consumers.
"We have been calling for all price comparison sites and collective switching schemes to comply with the Code so that everyone operates to the same high standards."