Kercher murder: Knox, Sollecito acquittals overturned Published duration 26 March 2013

media caption The BBC's Alan Johnston in Rome says there could still be "years to go" in the case

Amanda Knox and ex-boyfriend Raffaele Sollecito have had their acquittals for killing Briton Meredith Kercher in 2007 overturned and face a re-run of their appeal, Italy's top court has ruled.

The pair spent four years in jail but were freed on appeal in 2011 largely on the grounds DNA evidence was flawed.

Miss Knox said the news was "painful" but Miss Kercher's sister said she was happy with the decision.

Italian law cannot compel Miss Knox to return from the US for the review.

The American student lives in Seattle but, if convicted, Italy could seek her extradition.

In a statement, Miss Knox said: "It was painful to receive the news that the Italian Supreme Court decided to send my case back for revision when the prosecution's theory of my involvement in Meredith's murder has been repeatedly revealed to be completely unfounded and unfair."

She added: "No matter what happens, my family and I will face this continuing legal battle as we always have, confident in the truth and with our heads held high in the face of wrongful accusations and unreasonable adversity."

A lawyer for Mr Sollecito, Giulia Buongiorno, said: "Today is Raffaele's birthday and I hoped it was an occasion to tell him and his family that everything was fine and over. Unfortunately I had to let them know that our legal case is still on and obviously they were very upset."

Mr Sollecito - who is now studying in Verona - will not have to return to jail while the new appeals process goes ahead.

Kercher family lawyer Francesco Maresca welcomed the decision to overturn the appeal.

"This is an important day for the Italian justice system," he said outside the court.

Miss Kercher's older sister, Stephanie, welcomed the decision as a step forward.

"Whilst we are not happy about going back to court, and it will not bring her back, we have to make sure we have done all we can for her," she said.

Miss Knox, now 25, and Mr Sollecito, 29, were originally sentenced to 26 and 25 years in prison for killing and sexually assaulting Meredith Kercher.

Rudy Guede was convicted in a separate trial and sentenced to 16 years. The Ivory Coast national was found guilty of sexually assaulting and stabbing Ms Kercher. He admitted to being at the house on the night of the killing, but denies murder.

'Illogical'

Meredith Kercher, 21 and from Coulsdon in south London, was in Italy on a year abroad from Leeds University when she was killed in Perugia in November 2007.

She was found dead in her bedroom in the cottage she shared with Miss Knox. Her semi-naked body had more than 40 knife wounds, including a deep gash to the throat.

Prosecutors believed she was killed in a brutal sex game that went wrong.

media caption Stephanie Kercher: "It's a step forward for us"

Miss Knox and Mr Sollecito were acquitted in October 2011 by an appeals court that criticised the prosecution case and noted that the murder weapon had never been found, that DNA tests were faulty and that no murder motive was provided.

Prosecutors appealed against that ruling and argued at the Court of Cassation on Monday that the acquittals were "contradictory and illogical".

Addressing the court, prosecutors urged the judges to "make sure the final curtain does not drop on this shocking and dire crime".

The court examined whether there had been procedural irregularities, rather than looking at the details of the case, and it will announce the reasons for its ruling within 90 days.

Lawyers for Miss Knox and Mr Sollecito looked grim-faced on Tuesday as they tried to get the details of the ruling from the court.

Knox lawyer Carlo Dalla Vedova said the decision was "shocking" and wanted to know the "motivations" for the ruling.

"She thought the nightmare was over," he said, adding that it was unlikely the new hearing would be held before early 2014.

Miss Knox and Mr Sollecito spoke to each other by telephone after the ruling was announced, according to a friend of Mr Sollecito quoted by the Italian news agency Ansa.