She made the comments on ABC’s Good Morning America yesterday, a day after the guilty verdict against her was reinstated by an Italian appeal court.
Interviewer Robin Roberts held Knox’s hand at times as the 26-year-old American student said she would “fight this to the very end”. She also complained that the court’s decision had been unfair, as she had previously been cleared.
Knox was jailed for 28 years and six months and former boyfriend Raffaele Sollecito for 25 years after judges reinstated their murder convictions over Ms Kercher’s death in 2007.
The victim’s family want Knox to be extradited from the United States, but she insisted: “I will never go willingly back.”
Ms Kercher’s brother Lyle told a news conference in Florence it would be “strange” if Knox was not extradited. “If somebody is found guilty and convicted of a murder, and if an extradition law exists between those two countries, then I don’t see why they wouldn’t,” he said.
“I imagine it would set a difficult precedent if a country such as the US didn’t choose to go along with laws that they themselves uphold when extraditing convicted criminals from other countries.
“It probably leaves them in a strange position not to.”
But Knox told Good Morning America: “I’m going to fight this to the very end. It’s not right and it’s not fair.”
She said she had sent a letter to her lawyer to be forwarded to Ms Kercher’s family. “It’s in the mail,” she said. “Mainly I just want them to know that I really understand that this is incredibly difficult, that they’ve also been on this never-ending thing and, when the case has been messed up so much, like, a verdict is no longer consolation for them.”
Knox said she had watched the verdict on an Italian news channel and had translated it for the rest of her family.
Describing her response, she said: “My first reaction was, no, this is wrong and I’m going to do everything I can to prove that it is. And I felt very determined and my family felt very determined.
“But it was only on my way here that I really got my first cry.”
However, the victim’s sister Stephanie said the family did not want to read the letter. She also said they did not want to meet Knox, telling reporters at the news conference: “It’s not something that we would want to do at the moment, and I can’t say that we ever will.”
She said the family was still on a “journey for the truth’’ and admitted they were coming to terms with the possibility of never knowing what happened.
“You can’t ever really get to a point where you just start to remember Meredith, solely because it is following the case, coming over to Italy and everything associated with it.
“But the verdict has been upheld this time so we hope that, obviously, come the end of the trial, we are nearer the truth and an end so that we can just start to remember Meredith for who she was and draw a line under it, as it were.”
Ms Kercher, a 21-year-old Leeds University exchange student from Surrey, was found with her throat slashed in the bedroom of a house she shared with Knox in Perugia, central Italy, in November 2007.
Knox and Sollecito were originally found guilty of murder in 2009. They were cleared nearly two years later, but an appeal court ordered a fresh trial last March.
Prosecutors said Ms Kercher had been the victim of a drug-fuelled sex game gone wrong, but Knox and Sollecito have consistently protested their innocence and claim they were not in the flat on the night she died.
Rudy Guede, a drug dealer, is serving a 16-year sentence over Ms Kercher’s death, but the courts have said he did not act alone.
In an interview before the verdict was handed down on Thursday, Knox told the BBC: “They’ll have to catch me and pull me back, kicking and screaming, into a prison I don’t deserve to be in.”
Speaking outside the court, her lawyer, Luciano Ghirga, said he would launch an appeal.
“For those that, like me, are convinced that Amanda is innocent, it is a very difficult time,” he said. “We have to respect the verdict but we will challenge it.”
Sollecito was “prepared” for the verdict, his lawyer said.
However, Giula Bongiorno told reporters that the 29-year-old was “totally astonished why the court keeps changing mind in this way”.
Sollecito’s Austria trip on court day
Amanda Knox’s ex-boyfriend left Italy and drove to Austria while the appeal court decided his fate but eventually returned and surrendered his passport.
Raffaele Sollecito’s lengthy travels were revealed by police on the day Knox made clear she would never voluntarily return to Italy to serve her sentence.
Sollecito’s lawyer, Luca Maori, insisted his client had been near Italy’s north-eastern border with Austria on Thursday because that’s where his current girlfriend lived.
He said Sollecito later went voluntarily to police to surrender his passport and ID papers.
The head of the Udine police squad, Massimiliano Ortolan, said officers had been tipped off that Sollecito had checked into a hotel in Venzone, on the Italian side of the border, and they went to find him there, waking him and his girlfriend up and taking him to the police station in Udine.
No arrest warrant had been issued for him.