US murder suspect Amanda Knox has emailed an Italian court to say she is “afraid” to show up for her trial on charges of killing British student Meredith Kercher, judge Alessandro Nencini says.

Knox, who is a defendant, along with her former Italian boyfriend Raffaele Sollecito, is letting herself be tried in absentia.

She has signalled she would not return to Italy to serve her sentence if she is found guilty.

“I am not in the courtroom because I am afraid,” Knox said in a message in Italian that was read out in court by Nencini on Tuesday.

“I am afraid that you will be influenced by the vehemency of the accusations, that you will be blinded by their smokescreens.”

The judge dismissed Knox’s email as “unorthodox” and said those who “want to speak at a trial should come to the trial”.

He said lawyers for the defence vouched for the authenticity of the message.

Ms Kercher was 21 when she died.

She was found on November 2, 2007, half-naked and with multiple stab wounds, in the apartment she was sharing with Knox and two other female students in the central Italian university town of Perugia.

Knox and Sollecito were arrested days after the crime.

In 2009, they were jailed for 26 years and 25 years, respectively, after Perugia judges concluded in a first instance ruling that the pair, along with a third person, had killed Kercher during a group sex game.

They were acquitted in 2011 after an appeal court deemed incriminating DNA evidence to be unreliable.

Freed from prison, Knox returned to her home city of Seattle.

But the verdict was annulled in March by Italy’s top appeals body, which ordered a retrial and moved proceedings from Perugia to Florence.

Judges are expected to issue a new ruling in January, but it could be appealed again.