A judge in South Africa has thrown out the murder case against British businessman Shrien Dewani over the death of his wife while on honeymoon.

Anni Dewani, 28, was shot dead in Cape Town in November 2010 after the taxi she was travelling in with her husband was hijacked as they passed through a township late at night.

Three men, including taxi driver Zola Tongo, have already been convicted for their roles in the killing.

Prosecutors said Mr Dewani wanted out of the relationship and plotted with Tongo to kill his engineer wife in an apparent botched car-jacking.

But Mr Dewani, 34, from Westbury-on-Trym, near Bristol, has always denied this and pleaded not guilty to charges of murder, conspiracy to kidnap, robbery with aggravating circumstances, kidnapping, and defeating the ends of justice.

He claimed the couple were hijacked as Tongo was driving them through Gugulethu in his minibus.

He says he was released unharmed and his wife was driven away.

She was found shot dead in the abandoned minibus in Khayelitsha the next morning.

Tongo, who entered a plea bargain to testify against Mr Dewani, is already serving an 18-year jail term. 

Judge Jeanette Traverso dismissed the case against Mr Dewani after roundly condemning Tongo's evidence.

Announcing her ruling, the judge said: "The accused is found not guilty of this charge."

Giving her ruling in Cape Town on an application by Mr Dewani's defence lawyer Francois van Zyl to dismiss the prosecution, Judge Traverso said Tongo's claims about the murder were "riddled with contradictions" and "highly debatable".

The judge said the evidence presented by the prosecution fell "far below" the required threshold.

She said the only reason not to grant the application would be in the hope that Mr Dewani would implicate himself if he gave evidence.

But to do so would be a "manifest misdirection", she said.

Mr Dewani, who was finally extradited this year to face trial accused of planning the murder of his wife, listened intently as key evidence against him was criticised by the judge.

The family of Anni Dewani believe they have been failed by the justice system and are "deeply disappointed" after her husband was cleared of her murder.

Her sister, Ami Denborg said: "Today we feel as a family that the justice system has failed us and we are deeply disappointed.

"We came here looking for answers and we came here looking for the truth and all we got was more questions.

"We waited patiently for four years to hear what really happened to Anni and to hear the full story of what happened to our dearest little sister.

"All we wanted was to hear all the events and the hope of actually finding that out has kept us, as a family, going.

"Unfortunately we believe that this right has now been taken away from us."