(Cover) - EN Fashion - Tim Gunn has hit out at Taylor Momsen, calling her a diva and a brat.

The fashion mogul and Project Runway mentor is known for his frank talking and opinionated nature, and it seems that Taylor is the latest star to have offended him.

A few weeks back Tim shot a guest appearance in an episode of this seasons Gossip Girl, the US teen drama which Taylor stars in alongside Leighton Meester, Blake Lively and Jessica Szohr.

Tim says he was shocked to discover 17-year-old Taylor didnt seem to have learnt her script very well, and blasted her for spending too much time on her cell phone.

"What a diva! She was pathetic, she couldn't remember her lines, and she didn't even have that many. I thought to myself, 'Why are we all being held hostage by this brat? he revealed in an interview with E! News.

Fashion guru Tim is currently promoting his new book Gunn's Golden Rules: Life's Little Lessons for Making It Work, where he has also famously criticised the American Vogue editor Anna Wintour.

However, Tim did have some nice words to say, and described all of Taylors Gossip Girl colleagues as being a delight to work with. (C) Cover Media