© Franco Origlia/Getty ImagesAmanda Knox sits in Perugia's court of appeal during her appeal with Raffaele Sollecit against their convictions for murdering British flatmate Meredith Kercher in 2007.
Hectic scenes in Italian appeal by two of Meredith Kercher's convicted killers as lawyers swap claims of corrupt evidence

The appeal by Amanda Knox and Raffaele Sollecito against their convictions for killing British student Meredith Kercher has taken a surreal turn with two prosecution witnesses accusing a defence lawyer of offering to pay for a witness's sex change.

In a hectic session, Rudy Guede - the Ivorian already convicted for his role in the 2007 killing - started proceedings by accusing Knox and Sollecito for the first time in court of killing Kercher, prompting Knox to rise and tell the court she was "shocked and anguished" by his accusation. "He knows we were not there and were not involved," she said.

Guede was called from Viterbo jail, where he is serving 16 years, to respond to claims by a fellow inmate that he had confided that Knox and Sollecito had played no role in the murder of Kercher, whose throat was cut in the flat she shared with Knox in Perugia.

After entering the court in handcuffs and sitting 4.5 metres (15ft) from Knox, Guede read out a letter he had written to his lawyers in which he called those claims "stinking rubbish".

As well as Guede's fellow inmate, the court has previously heard from a jailed Neapolitan mafioso, Luciano Aviello, who claimed that Kercher was killed not by the Ivorian national, Knox or Sollecito but by his own brother during a burglary gone wrong.

A fellow inmate of Aviello's called by the prosecution on Monday said mafia member had told him he had been offered €70,000 (62,400) by Giulia Bongiorno, an Italian MP and lawyer defending Sollecito, to invent the story. Cosimo Zaccari - who is in jail for fraud, libel, criminal conspiracy and receiving stolen goods - said Aviello had confided that he was "contacted to create confusion in the trial".

Zaccari - who described himself as a former police informer and restaurant owner - was followed on to the stand by Alexander Ilicet, a Montenegrin who shared a cell with Aviello and claimed his cell-mate had boasted of being offered €158,000 by Bongiorno that he had planned to use for a sex change.

Francesco Maresca, a lawyer representing the Kercher family, called the statements "extremely credible" but Bongiorno said: "We are beyond the realms of the reasonable," adding: "Not even the prosecutors appear to believe this story and I will be reporting this libel."

Madison Paxton, a childhood friend of Knox's who was in court, accused the prosecution of resorting to unreliable witnesses. "Every time we are doing well in the trial they try something desperate, like caged animals," she said.