Labour MP Shane Jones is standing down from his opposition spokesman responsibilities while there's an investigation into the way he approved a New Zealand passport for a Chinese businessman.

Mr Jones was a minister in 2008 when he granted a passport to Yong Ming Yan, who is on trial facing immigration charges.

It has been revealed Mr Jones, who was associate immigration minister at the time, ignored the advice of his officials when he approved the passport application.

He says he had been told the man might have his organs harvested if he returned to China.

Labour leader David Shearer has asked Auditor-General Lyn Provost to investigate the passport granting process.

"Shane has encouraged me to take this action because he has been left in the impossible position of not being able to clear his name," Mr Shearer said on Wednesday.

"While the inquiry is under way, Shane Jones will stand down from his portfolio responsibilities and from Labour's front bench."

Yan, also known as Bill Liu, is on trial in the High Court at Auckland on four charges of using false declarations on immigration papers and one charge of using false written statements to get citizenship.

The judge's decision is expected on Thursday.