Four energy firms facing probe
Ofgem has launched an investigation into four energy companies amid concerns of mis-selling to consumers.
The energy regulator said it was prepared to take "strong action" if it found that npower, Scottish Power, Scottish and Southern Energy and EDF Energy were failing to comply with new obligations to prevent mis-selling.
It has set up a hotline for consumers who are concerned about the sales approaches employed by suppliers to sell energy contracts, either face to face or by telephone.
The move follows tougher obligations imposed on suppliers in October as part of Ofgem's investigation into the energy retail market.
Ofgem spokesman Andrew Wright said: "Suppliers have existing obligations to detect and prevent mis-selling, and new licence conditions were brought in following our probe to further increase protection for customers.
"We expect all suppliers to comply with these tougher obligations but if our investigations find otherwise we will take strong action."
Under the new obligations, suppliers must be "proactive" in preventing mis-selling to customers, both face to face and over the phone.
Suppliers who are selling contracts face to face must provide customers with an estimate before any sale is concluded.
Customers should usually also receive a comparison of the supplier's offer with their current deal.
Ofgem and consumer organisation Consumer Focus have also published a leaflet with practical information and advice for consumers when an energy sales representative calls at their door or telephones them at home.