Centrica aims to sell UK nuclear stake by end of 2020
France's EDF owns the other 80 percent of the nuclear plants, which generate around 20 percent of Britain's electricity.
"We have had a number of people calling us saying they would be interested but we haven't started marketing it yet," Centrica CEO Iain Conn said on the sidelines of the FT Energy Transition Strategies Summit in London without identifying any interested parties.
Conn said as early as last June that the company would consider selling the stake if the right offer came along.
Centrica is moving away from large, centralised power generation while increasing its services offerings.
The company sold its last large power stations last year, with its generation now focusing on smaller, flexible plants that can react quickly to produce electricity at peak times when it is most needed.
Analyst have said it could be difficult to attract buyers for the nuclear assets, with large financials shying away from nuclear investment and half of the plants expected to close in 2024.
Last week Britain said it would consider investing in a new plant to be built by Japanese company Hitachi in northern Wales, with private investors reluctant to take on the huge costs of new nuclear power infrastructure.
(Reporting by Susanna Twidale; Editing by Alexander Smith and David Goodman)
By Susanna Twidale