Scottish Power, EDF Energy, Scottish and Southern Energy and RWE Npower will be probed on their compliance with the sales regulations of Ofgem.
Last October, the regulator introduced obligations that require suppliers to be proactive in preventing mis-selling to customers both face to face and over the phone.
Ofgem senior partner (markets) Andrew Wright said that suppliers have existing obligations to detect and prevent mis-selling and new license conditions were brought in following Ofgem’s 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.”