Upmarket Swiss chocolate maker Lindt & Sprüngli has signed up tennis star Roger Federer to serve as global brand ambassador for its Lindt chocolate.

This is the first time in the company's history that it is has signed a "celebrity" deal, the group said today (29 October).

The contract details of the long-term agreement have not been made public.

"The global fame of top sportsman Federer makes this partnership a highly promising opportunity for Lindt & Sprüngli to further enhance the global popularity of its premium chocolates and become still more firmly established in key global markets," Lindt & Sprüngli said.

The deal with Federer will be used as an additional communication instrument in Lindt's global marketing effort, the company said.

Lindt is the latest food maker to sign up Federer. He joined forces with Swiss dairy group Emmi in 2003 to plug a range of products, including yoghurt and muesli.

An Emmi spokesperson told just-food that the contract ended in the summer and that it would not be renewed.

"We don't have a contract with Federer anymore," the spokesperson said. "It ran out two months ago. We have been working with him the for the last six years and so the contract ended as planned."