The Department of Conservation has confirmed a staffer seconded to Kiri Allan's office chose to leave amid concerns about "working relationships" there.
Allan said in a statement that she had "great working relationships with my office crew".
"Like in many offices and workplaces, there are sometimes challenges with working relationships and the Beehive is no different," she said.
"I value my crew and I have always been clear that I have high expectations of senior public servants, as I do myself. New Zealanders rightly deserve results from the Government and my job is to deliver those outcomes."
The Prime Minister's Office says no formal complaints have been made by either departmental or ministerial staff about Allan, but work has been done to improve working relations in the office.
The revelation comes as Allan shares she has been away from Parliament after "struggling with mental health".
In a statement to Newshub on Wednesday afternoon, DoC Director General Penny Nelson said she became aware "that concerns had been raised about the working relationships with the minister in the office and that it was not running as smoothly as it might".
"One person chose to end their secondment early due to the working relationships in the office."
This occurred more than a year ago. Allan was the Conservation Minister between November 2020 and June 2022.
After these concerns came to her attention, Nelson said she had discussions with colleagues, including with those at Internal Affairs which manages ministerial services, regarding "support in the office".
"No further concerns were subsequently brought to my attention, and I understand relationships improved," Nelson said.
A spokesperson for the Prime Minister said there have been "no formal complaints made by departmental or ministerial staff about Minister Allan".
"Some issues have been raised about how to improve working relations in the Minister’s office. Work was done to improve the situation and no further issues were raised.
"Parliament is a high-pressure environment and Minister Allan is passionate about her work, however this has never led to any formal complaints and past issues have been resolved without the need for significant escalation."
The details, first published by Stuff, came as Allan posted on Instagram that she had been "struggling with mental health and wellness" over recent weeks and had taken some time off this week.
She is now "feeling a lot better" and intends to return to work on Thursday.
Allan said her issues were "triggered" by personal and external circumstances, including issues like the cyclones hitting the East Coast region.
"Sometimes things accumulate, and I hit a wall a few weeks ago. I kept going, showing up to events, smiling, giving speeches. But about a week ago, I had to be pretty honest with myself that I needed to put my mental well-being at the forefront of my focus."
Allan said she spoke to colleagues, friends and family about the situation.
"That was bloody hard. It felt a little embarrassing admitting I wasn't doing okay. But what followed was an overwhelming response of aroha - and I am so glad I shared with people I love to help pull me out of my head."
Newshub has contacted the Prime Minister's Office for further comment.
Allan first entered Parliament in 2017. She began taking on ministerial roles after the 2020 election, including Conservation and Emergency Management.
She is the current Justice Minister and represents the East Coast electorate.
Allan faced scrutiny last month after she criticised RNZ's culture and treatment of Māori staff at a farewell event for her fiancée, Māni Dunlop. She later apologised and said that while she was there in a personal capacity, her comment could have been interpreted as her telling RNZ how to manage the company, which is independent.
Prime Minister Chris Hipkins said at the time he'd accepted Allan's apology. He said while she was invited in a personal capacity, in that instance it would've been better if she had chosen not to speak, given her ministerial position.
