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
The Duchess of Cornwall attended the sell-out concert in Edinburgh.
The US firm’s winning bid was £17.28 per share, beating Fox’s £15.67 offer.
The man died after being taken to hospital, while a teenager also stabbed in the incident is said to have non-life-threatening injuries.