Energy customers should not be seen as "cash cows, to be squeezed in the pursuit of a higher return for shareholders", a Government minister will warn today.

Energy Secretary Ed Davey will tell Energy UK's annual conference that trust between firms and customers was breaking down, amid continued controversy over soaring bills.

Power companies have to make profits so they could invest in energy infrastructure, secure supplies and develop more energy efficient technologies, as well as create jobs, he will tell the London conference, adding: "But those profits cannot come at the expense of the elderly, the vulnerable, and the poorest in our society.

"Customers are not just cash cows, to be squeezed in the pursuit of a higher return for shareholders.

"Trust between those who supply energy and those who use it is breaking down.

"It is so difficult for people to work out what exactly they are paying for that they fear the big energy companies are taking them for a ride when bills go up.

"Fair or not, they look at the big suppliers and they see a reflection of the greed that consumed the banks. So this is a 'fred the shred' moment for the industry.

"You deliver an essential public service, so your industry must serve the public - and the public must have trust in what you do."