Energy giant E.ON is to cut 500 jobs in its UK support functions to reflect the "changed nature of the business" following the sale of its distribution arm earlier this year.
The company said it is seeking up to 500 voluntary redundancies, likely to impact mainly at its head office in Coventry and other sites near Nottingham.
The announcement follows the sale of E.ON's distribution arm, Central Networks, in March and the subsequent concentration on the customer-facing business.
Chief executive Paul Golby said: "We had to undertake a deep and rigorous review of how much money we spend in order to ensure we keep costs as low as possible for our customers, become a more agile organisation and build a sustainable business in the UK.
"While I'm very aware that this will be a difficult time for our colleagues, it is our aim to keep uncertainty to a minimum and to achieve these redundancies by voluntary means."