Valentino was giving a press conference at the Venice Film Festival, which has screened an intimate fly-on-the-wall film documenting the final couple of years before his retirement.

Roberts accepted an Oscar for her performance in Erin Brockovich in 2001 wearing an elegant vintage black and white Valentino gown.

When asked to name the actresses who stood out for him, the designer said: "I have to be very sincere, the person that makes me feel very happy, also because (she) chose vintage, was Julia Roberts, when she got the Academy Award... I was very excited to see her when she appeared with my dress."

Valentino: The Last Emperor is billed as a glimpse into a world of bygone glamour.

The designer announced his retirement in 2007, two months after a lavish three day celebration in Rome of 45 years in the fashion industry which drew a huge celebrity turnout.

Filmed from June 2005 to July 2007, the crew shot hundreds of hours of footage of one of Italy's most prominent designers and his entourage, including his six pug dogs, which follow Valentino everywhere and even have their teeth brushed.

As well as lifting the lid on the fashion world, it shows tender moments from Valentino's 50-year relationship with Giancarlo Giammetti, who said the film was "not a story of money or fashion - it is a story of love".

The designer and Giammetti began as boyfriends in the early 1960s and became life business partners who built up a billion dollar fashion business.

The film captures intimate moments in the pairs' lives, at times seeing them emotional, as well as taking a peek at their disagreements and their humour.