Camelot marketing director Jon Kinsey has resigned to become marketing and strategy director at British Gas Trading.
Human resources director Nigel Brocklehurst and quality director Pat Morrish are also quitting.
News of the departures comes one week after communications director David Rigg and security director Neil Dickens announced they were leaving.
Kinsey says he has been involved in the marketing of the National Lottery since he joined Camelot three years ago from Hasbro, where he was vice-president for the games division.
However, he adds: “The gas market is opening up to competition. It is more exciting than the Lottery. Over the next three years the changes in the market will be enormous.”
At British Gas Trading, Kinsey replaces Roy Gayton, who joined in June as interim marketing director (MW June 5).
Rigg denies the exit of five directors signals a mass walkout from the company, which has faced harsh public criticism for profiteering and awarding huge pay rises to top directors.
Morrish and Dickens are retiring, Brocklehurst is moving to telecoms company Ionica, and Rigg, the only main board director to go, is considering other options, including becoming a consultant.