Eon Energy and Npower will leave Energy UK at the end of this month, Utility Week can reveal.
Eon has confirmed it can no longer afford the membership fees, which are understood to be around £300,000.
A spokesperson said: “We constantly review our costs in order to continue to deliver value for money for our customers.
“As part of this, we have decided being part of Energy UK is something we can no longer afford and we have therefore made the reluctant decision to leave Energy UK.”
As Npower’s retail arm will be part of Eon, it too will also leave the organisation.
Both Eon’s chief executive, Michael Lewis, and Npower boss Paul Coffey resigned as directors of the organisation today (17 December).
An Energy UK spokesperson said: “It is a challenging environment for many in the retail sector and unfortunately Eon and Npower will both step down from Energy UK membership in the new year.
“We will continue to maintain our positive relationships with the companies and hope they may rejoin in the future when the financial environment is less challenging.”
Utility Week understands that RWE, which is made up of RWE’s, Innogy’s and Eon’s generation assets will continue to be full generation members of Energy UK.
Eon and Npower are not the first suppliers to leave Energy UK. First Utility previously left the trade body before returning under the banner of Shell.