LONDON (Reuters) - Octopus Energy has become Britain's largest domestic electricity supplier by customer numbers, latest Ofgem data showed after the company added 1.3 million customers following its takeover of Shell Energy late last year.

Octopus Energy, which is eight years old, has overtaken Centrica's British Gas which had been the largest electricity supplier for almost the past twenty years, Ofgem data shows.

At the end of 2023 Octopus Energy had a 22% share of the electricity market compared with British Gas at 20.3% and E.ON with 16.8%, the data showed.

Shell last year sold its home energy business in the UK and Germany to Britain's Octopus Energy Group as part of a deal in which the two companies explore a partnership on EV charging.

Returns in the British energy retail sector have been under pressure over the past few years as companies struggled with soaring wholesale costs and a cap on the prices they can charge customers imposed by regulator Ofgem.

British Gas remains the largest domestic gas supplier with a 27.8% market share followed by Octopus at 22.2% the data showed.

(Reporting By Susanna Twidale; Editing by Kirsten Donovan)