National MP Sam Uffindell has been stood down pending an investigation into allegations about behaviour towards a female flatmate in 2003.
National leader Christopher Luxon announced the news in a statement late on Tuesday night.
“This evening my office became aware of very concerning accusations made to RNZ about behaviour shown by Mr Uffindell toward a female flatmate in 2003 while at university," the statement read.
“Mr Uffindell disputes the allegations and in the interests of natural justice, an independent investigation will now be undertaken to determine the facts. While this process is underway, Mr Uffindell will be stood down from caucus.
“The investigation will be conducted by Maria Dew QC and I expect it to take two weeks."
Luxon added the terms of reference for the investigation still need to be set.
In a separate statement, Uffindell said he "enjoyed a student lifestyle" while at Otago University.
He said this included drinking and, at times, smoking marijuana.
"While in second year, a number of flatmates fell out – and two of the flatmates left midway through the year," Uffindell said.
"I reject any accusation that I engaged in behaviour that was intimidatory or bullying. This simply did not happen.
"While there is an investigation into these accusations I will not make further comment."
Party president Sylvia Wood said Luxon had told her Uffindell would be stood down from caucus "pending an investigation into further allegations about his past behaviour raised in the media".
"In the interests of letting due process run its course, I will not be making additional comment on this issue while the investigation is carried out."
Earlier on Tuesday, Uffindell admitted being a bully at school after revelations he was involved in a school assault which saw him being asked to leave Auckland's King's College when he was 16.