The Italian lawyer representing Amanda Knox has launched an appeal against her conviction for slander, a spokesman for the American said.

In October, an Italian appeals court overturned the young Seattle woman's murder conviction over the 2007 death of her British housemate, Meredith Kercher, in Perugia.

But the same court upheld Knox's conviction for slander - for falsely accusing bar owner Diya "Patrick" Lumumba of involvement in the killing.

Lumumba was freed after two weeks in prison due to lack of evidence.

Knox later said she was "manipulated" during her lengthy police interrogation.

Knox family spokesman Dave Marriott confirmed an appeal over the slander conviction was filed yesterday but he did not know when the Italian court might consider it.

Knox returned to Seattle after her murder conviction was overturned. The former exchange student had been in custody since 2007. Ms Kercher, from Coulsdon in Surrey, was found dead in her Italian bedroom on November 1, 2007.

An Italian judge set Knox's sentence for slander at three years, which was less than the time she had spent in prison. That meant she could leave Italy.

In its ruling last autumn, the Italian appeals court also acquitted Knox's then-boyfriend, Raffaele Sollecito, over Miss Kercher's murder.

A third defendant, Ivory Coast-born drifter Rudy Guede, was convicted in a separate trial of sexually assaulting and stabbing Miss Kercher, of Coulsdon, Surrey. His 16-year prison sentence - reduced on appeal from an initial 30 years - was upheld by Italy's highest court in 2010.