With energy supplier EDF reporting half-year profits before interest, tax, depreciation and amortisation of 8.6 billion euros, or £7.5 billion, customers might feel their "hackles rising", Consumer Focus has claimed.
Audrey Gallacher, director of energy at the lobby group, noted that many EDF customers will be wondering now whether the provider is likely to follow in the footsteps of other energy suppliers and raise prices.
She commented: "Consumers won't care which end of the business the profits are being made at, they need to know that whatever the result they are getting a fair deal and that they can trust energy firms."
This means closer scrutiny of the market is required to ensure it is fair, open and competitive, Ms Gallacher added.
British Gas, ScottishPower and SSE have already hiked tariffs.
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