(Reuters) - Private equity firm Advent International is preparing a takeover offer for UK-based food and beverage ingredients maker Tate & Lyle, the Financial Times reported on Wednesday, citing two people familiar with the discussions.

Shares in Tate & Lyle, which supplies ingredients for Splenda, the sweetener in Diet Coke and other sugar-free drinks, jumped 11.5% to a near eight-year high on the news.

The US-based buyout firm is in the early stages of its bid preparations, according to sources, who cautioned there was no certainty that a firm offer would be made, the report added.

The offer could value Tate & Lyle above its 2.8 billion pounds ($3.65 billion) market capitalization, according to the Financial Times.

Both Tate & Lyle and Advent declined to respond to Reuters' requests for comments.

Tate & Lyle in June agreed to buy U.S.-based CP Kelco for $1.8 billion to boost its speciality ingredients business and tap demand for plant-based products.

($1 = 0.7676 pounds)

(Reporting by Prerna Bedi in Bengaluru, additional reporting by DhanushVignesh Babu; Editing by Shinjini Ganguli)