Simon Bridges could face jail if Jami-Lee Ross' corruption claims are true - law expert

National leader Simon Bridges could face jail if the sensational corruption allegations rogue MP Jami-Lee Ross levelled at him are found to be true, a law expert says.

Mr Ross accused his former boss Mr Bridges of electoral fraud in a bombshell news conference held on Tuesday morning.

University of Otago law professor Andrew Geddis says the alleged offence carries a two-year prison sentence, and would “lead to automatic expulsion from Parliament”.

Prof Geddis told Newshub the ex-National MP is accusing Mr Bridges of breaching the Electoral Act.

"Essentially the allegation is that the leader of the Opposition Party committed a very serious offence under our electoral laws," he said.

"Knowingly filing a false donation return under the Electoral Act is a corrupt practice, and entering into an arrangement to try to do so is to be a party to that corrupt practice.

"If these allegations are founded, Simon Bridges has to resign, full stop."

Prof Geddis declined to comment on whether he believed the accusations were in fact founded, though he did note that what happens on Wednesday could prove revealing.

"If Jami-Lee Ross doesn't front up to the police tomorrow with the evidence he says he's got, then we can draw some conclusions about the allegations that were made," he said.

"The mere fact these allegations have been raised... hasn't happened before in New Zealand politics," he added.

"That makes it quite an extraordinary day."