The trial of a British businessman accused of murdering his wife on their honeymoon may be on the verge of collapse after defence lawyers signalled for the case to be thrown out.

Care home entrepreneur Shrien Dewani, 34, has always denied plotting with others to kill new bride Anni Dewani on a luxury honeymoon in Cape Town, South Africa, four years ago.

Prosecutors claim the millionaire, who is bisexual, wanted out of his marriage and arranged a "hijack-gone-wrong" in which Anni would be killed and her husband escape unharmed.

But Western Cape High Court judge Jeanette Traverso has dismissed sections of the state's case, describing evidence about Dewani's sex life as irrelevant, while prosecution witnesses have included men already convicted of Anni's murder.

At the conclusion of the state case today, defence counsel Francois van Zyl said they would make an application to the judge under section 174 of the Criminal Procedure Act. It provides that the court may return a not-guilty verdict if the judge feels there is insufficient evidence to convict at the close of the prosecution's case.

Judge Traverso said submissions will be heard on Monday.

Dewani is on trial for allegedly plotting with shuttle taxi driver Zola Tongo, Mziwamadoda Qwabe and gunman Xolile Mngeni.

The defendant, extradited from the UK after a lengthy Home Office battle, claims the couple were hijacked while Tongo drove them through the rough Gugulethu township in his taxi on Saturday, November 13, 2010.

He was released unharmed and Anni was driven away. Her lifeless body was found in the abandoned taxi in Khayelitsha the next morning - she had been shot.

The state alleges Dewani conspired with others to stage the hijacking, for which he paid 15,000 rand - less than £1,000 at the 2010 exchange rate. Dewani maintains the money was actually for a surprise helicopter trip which Tongo was helping to arrange.

Tongo is serving an 18-year jail term and Qwabe is part-way through a 25-year jail term. Mngeni was serving life in jail for firing the shot that killed Anni, but died in prison from a brain tumour on October 18.

Monde Mbolombo, a self-confessed "link man" in the plot, has already been told the immunity granted to him in return for being a state witness may no longer stand.