National Party MP Nick Smith has announced he will retire from Parliament amid a confidential inquiry into a verbal altercation he had in his office last year.
He says he will retire on June 10 for "personal and professional reasons", one of which is the inquiry.
"Parliamentary Services have been conducting a confidential inquiry into a verbal altercation in my Wellington office last July that has not concluded," he says.
"I was advised on Friday that the inquiry and its details have been leaked to the media for release tomorrow. It is inappropriate for employment disputes to be litigated in public.
"I will put on the record that I regret the incident, I apologised at the time and I apologise again today. I have decided the best course of action for the parties involved, the National Party, my family and myself is to retire now."
Smith says he was disappointed to lose his Nelson seat at the 2020 election after representing the region for 30 years and he had decided to retire earlier this year - "the only question was when".
"Politics does place a significant burden on family and I am incredibly grateful for the support of my wife, children and wider family," he says.
"There have been recent changes in family circumstances which require me to give greater support."
Over his time in Parliament, Smith says it's been a "huge privilege" to be an MP, to serve as 15 different ministers under four prime ministers, and to represent Nelson.
He adds he is looking forward to rejoining his family's crane and construction businesses in New Zealand, Australia and in the Pacific.