Ed Davey, the Secretary of State for Energy and Climate Change, has told Daybreak he is "very worried" about people's electricity and gas bills and said the "big six" energy companies needed to be more transparent.
"They need to be held accountable for the profits they make and they need to declare them in a much clearer way," The Liberal Democrat MP said.
More top news
In the unexpected announcement on Monday, Mr Key said it was the "right time" to leave politics.
As the Government's Brexit appeal comes to the Supreme Court, here's a look at what you need to know.
According to local reports, the man was found by friends in their accommodation in Val Thorens resort in the Alps on Sunday morning.