Gwyneth Paltrow has been branded a ''backstabber'' by 'Difficult People' creator Julie Klausner.

The writer-and-comedian claimed Hollywood star ''pretend'' to be friends with one another, while telling a different story in private, and accused the 'Iron Man 3' star of being one of the worst.

She told the New York Post newspaper's Page Six column: ''They pretend that they are [all great friends], but the stuff that is said about people behind the scenes is really terrible.

''Well -- Gwyneth Paltrow -- there's many a tale to tell. All kinds of backstabbing.''

Julie - who also stars in 'Difficult People' alongside Billy Eichner as two struggling New York comics who hate everyone - didn't give any specific details about Gwyneth's alleged antics but suggested she may be different these days.

She simply said: ''She's into [Eastern therapy] cupping now -- maybe she's cupping instead of backstabbing.''

The 38-year-old star has previously hit out at the 43-year-old actress on Twitter.

In March she posted: ''Click here to witness the chemistry between Gwyneth Paltrow and Jimmy Fallon AKA the comedy version of ammonia and bleach!''

Gwyneth - who has children Apple, 12, and Moses, 10, with ex-husband Chris Martin - recently spoke about how she has taken ''a lot of s**t'' over her lifestyle website Goop.

She said: ''I think it is challenging for people to change careers. If you're in the public eye and you make a shift I think it's confusing for a minute... In a lot of ways I was the first, so I took a lot of sh*t.''

And the blonde beauty's mother, Blythe Danner, recently suggested her daughter's critics are jealous and ''intimidated'' by her success.

She said: ''So much of it is just trying to sell papers or whatever that's called over the Internet. I know she's the most extraordinary girl who can do everything. Incredible mother, she's raising hundreds of thousands of dollars for my husband's oral cancer foundation -- things she doesn't talk about a lot

''I'm so proud of her. I think she's so accomplished that people get kind of intimidated by it.''