Energy regulator Ofgem has proposed that the Big Six energy firms should be investigated by the Competition and Markets Authority.
In an open letter to Britain's main energy suppliers, the regulator's chief executive officer Dermot Nolan said they were concerned that companies were "not passing on savings to customers".
He said: "A concern that savings were not being passed on to customers was one of the reasons why we have proposed a referral of the energy market to the Competition and Markets Authority for investigation."
More top news
Northwestern Scotland and Northern Ireland face a rain-hit weekend, while the rest of Britain enjoys some bright but generally dry weather.
All this week while reporting, I have been taking photos. They offer powerful portraits of the lives affected by the desperate outbreak.
Some of the world's biggest football clubs will ask FIFA to move the 2022 World Cup to spring.