MILAN (Reuters) - Valentino Garavani, one of fashion's most famous designers, will resign in January from the couture house he founded after 45 years dressing European royalty and Hollywood stars.

The Italian, who is 75, said in a statement it was "the perfect moment to say goodbye to the world of fashion".

Valentino held three days of parties in July celebrating 45 years of his career as a couturier and had been widely expected to announce his retirement then.

Insiders have said it would only be a matter of time before he left with Valentino Fashion Group's new owners, private equity firm Permira, looking for a younger, more commercially-minded figure to lead its expansion into new countries and new product lines during an industry boom.

Italian newspapers and industry sources have suggested former Gucci designer Alessandra Facchinetti is in the running.

Valentino said on Tuesday he was already working on the womenswear ready-to-wear collection for Paris in October and a final haute couture show to be shown in January.

Valentino's signature scarlet evening gowns and conservative style have kept him a favourite for red carpet events, where he has dressed a cast of famous names spanning Jacqueline Kennedy Onassis, Audrey Hepburn, Elizabeth Taylor to Cate Blanchett and Julia Roberts.

"I have been lucky to have turned my teenage passion into my work ... and to retain my own style, despite the big changes in the world of fashion," Valentino said.

He added that he would be working on new projects in the future, some of which would be connected to fashion.