Amanda Knox has told an Italian appeal court she is innocent of the murder of British student Meredith Kercher.

The American student is serving a 26-year-long sentence and was convicted with her former boyfriend, Italian Raffaele Sollecito, who got 25 years for his part in the murder. They were found guilty of killing 21-year-old Meredith in what prosecutors said was a frenzied sex game that spiralled out of control.

Kercher's body was found partly clothed in November 2007. She was locked in her blood-spattered bedroom in a house she shared with Knox and two other students in the Umbrian hilltop town. There was a deep stab wound to the throat.

Knox's lawyers believe they have new evidence to clear her of murder and will also try to introduce a new witness. They will also call for a full review of the forensic evidence used in the trial, including the disputed traces of DNA found on a knife allegedly used in the murder, and on the clasp of Miss Kercher's bra.

Addressing the court in Italian, Knox said: "I never expected to find myself here, convicted for a crime I did not commit. In these three years, I have learned your language and I have observed the procedures but I will never get used to this shattered life.

"To Meredith's family and dear ones, I want to say that I am very sorry that Meredith is not here anymore, I cannot tell how you feel, but I, too, have younger sisters and the thought of their suffering and infinite absence terrifies me."

She added: "It is incomprehensible and unacceptable what you are going through and what Meredith suffered. I, too, remember Meredith and in my heart suffer for all of you.

"Meredith was kind, intelligent, sympathetic and always there for you, it was she who invited me to see Perugia as a friend of her's. I'm grateful and honoured to have been able to enjoy her company and being able to know her."

If Knox's appeal is rejected, she could face a longer sentence behind bars. Her conviction sparked outrage in the US and her family strongly condemned Italy's judicial system. Secretary of State Hillary Clinton said the US government would follow her appeal.