Janet Hubert, who was the first actress to play Aunt Vivian on "The Fresh Prince of Bel Air" and talk show host Wendy Williams. (Handout, WENN.COM)

Actress Janet Hubert has taken aim at U.S. talk show host Wendy Williams, branding her a "demon" after the outspoken presenter quizzed her The Fresh Prince of Bel Air co-star Tatyana Ali about the veteran's abrupt exit from the show 20 years ago.

Ali, who played Hubert's onscreen daughter, was a guest on The Wendy Williams Show earlier this week and she was left squirming as the host revisited talk of onset tension between her TV mom and the sitcom's star, Will Smith, as Williams tried to find out the real reason why Hubert was fired from her role as Aunt Viv in 1993.

Her line of questioning irked Hubert, who was subsequently replaced on the show by Daphne Maxwell Reid, and she has since fired off a vicious open letter blasting Williams for opening old wounds.

The angry, rambling missive, which has been posted online, reads in part: "You are such a demon Wendy. You are wicked, awful, conniving, sinister, spiteful, jealous of every other woman. Simply put, Wendy you are a virus. You are not nor have you ever been a true woman. It seems as though your audience thirsts for the blood of others, as they are prompted to clap and hoop and holler at your shows and wigs and clothes..."

Hubert then attacked Williams for allegedly attempting to take the crown of retired talk show queen Oprah Winfrey.

She continued, "Girl, you will have some stars on your show and demean them before they even make it back home. I just would like to know who died and told you that you were reborn as Oprah. You want to be Oprah so bad that you would kill for it and you will kill anyone to achieve success. Sister, you will never be another Oprah. Oprah lifted her audience up and exuded an air of class."

Williams has yet to respond to Hubert's open letter.

She's not the first star to take issue with Williams this month (Mar) - Lil Kim attacked the talk show host for openly criticising the rapper's new look on her show following reports suggesting the hitmaker had had extensive cosmetic surgery on her face.