Young millionairess Mary-Kate Olsen is obsessed with supermodel Kate Moss and is desperate to play her idol on the big screen.

The teen star wants to make a movie about Moss and star in it herself - to show people she can really act.

A friend of Olsen says, "Mary-Kate absolutely adores Kate Moss."

"She was so worried about her when she went into rehab (for cocaine use) and she even wrote her a really nice letter offering her support and friendship."

The 19-year-old believes the two have a lot in common and are both "independent, free spirits".

The source adds, "Mary-Kate think that she would be able to bring the right edginess and depth to the role."

"She sees Kate as a survivor, just as she is herself."