Knox had appealed verdict in slander retrial in last bid to clear her name.

Amanda Knox has lost her bid to overturn a slander conviction in relation to the 2007 murder of British student Meredith Kercher after Italy's top court upheld the ruling on Thursday.

American Knox, 37, spent four years in prison in Italy after being convicted of the murder of 21-year-old Kercher, before being cleared of the crime in 2015 along with her Italian former boyfriend Raffaele Sollecito.

Knox returned to Italy last June in an attempt to quash a three-year defamation conviction for falsely accusing Congolese bar owner Patrick Lumumba of killing Kercher, telling reporters that she wanted to clear her name "once and for all of the false charges against me."

Lawyers for Knox claimed that she had been under police duress when she named Lumumba who was jailed for two weeks in 2007 before being released.

However Knox lost her bid to overturn the slander conviction after a court in Florence upheld the ruling, prompting her to appeal the verdict in one last attempt to clear her name.

Knox, who returned to the US in 2011 after being freed by an appeals court in Italy, followed Thursday's court proceedings from home.

Cover image: Amanda Knox in court in Perugia, Italy, 22 January 2011. Photo credit: Alessia Pierdomenico / Shutterstock.com.