Knox's stepfather Chris Mellas said on Monday the film was 'disgusting' and damaged her chance of being tried without bias. He said Knox had watched the trailer and was disturbed by it.

Lawyers for Knox and Meredith Kercher's family said they had formally demanded in separate letters sent to U.S. television network Lifetime last week that the film be scrapped, threatening legal action if it is not canceled.

"Amanda Knox: Murder on trial in Italy," with Hayden Panettiere starring as Knox, is due to air on February 21.

"To have a film so soon, on such a violent death and with the memory of this tragedy so fresh in the family's mind seems totally inappropriate and unjustified," Francesco Maresca, a lawyer representing Kercher's family, told Reuters.

Lifetime said on Monday it had no comment on the requests by the lawyers.

Kercher, 21, was found half-naked and with her throat slit in a flat she shared with Knox in the university city of Perugia, on November 2, 2007.

Knox, now 23, and her former Italian boyfriend Raffaele Sollecito have been sentenced to 26 and 25 years in jail respectively. Prosecutors say the killing was the result of an extreme sex game that turned violent.

The film's producers said last month they did not contact the families of either Knox or Sollecito.

Instead they worked from detailed Italian court documents and media reports about the case, and said they had been careful in telling the story in an impartial way.

Stepfather Chris Mellas told Reuters; "At the last visitation, I sat down with her and she mentioned that she had seen a little bit of it and she was absolutely horrified by the clips of the movie that she saw.

"She finds it really disturbing that these people would decide to put a movie out there, say that it is in essence the true story, like a docu-movie or something, when in reality they have not spoken to anybody. So, how could it be?"

The appeals trial is under way, and the Perugia court has ordered DNA evidence in the case to be re-examined as requested by Knox's and Sollecito's lawyers.

"We are against the film because the trial is at a very delicate stage, and one cannot talk about the facts as if there was a crystal-clear truth," said Maria Del Grosso, one of Knox's lawyers.

"Also, the violence of the scenes (in the film's trailer) forced us to make this decision," she said.

(Published by Reuters - February 7, 2011)