Simon Bridges says he regrets calling a National MP's health issues "embarrassing".
On Tuesday, he announced that Jami-Lee Ross would be taking leave from Parliament for unspecified health reasons.
He described Mr Ross' health condition as "perhaps actually embarrassing - a lot embarrassing, potentially".
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When his repeated use of the word "embarrassing" was questioned by reporters, he backtracked and said it was "maybe not the right word".
"We all have our own views on these things - actually, it's not really for me to characterise it," he said.
His use of the word was heavily criticised in the following days. The AM Show host Duncan Garner said it was a "glaring mistake" and a potential breach of Mr Ross' privacy.
A source contacted Garner on Wednesday, claiming that Mr Ross was "highly pissed off" with Mr Bridges' comments.
Prime Minister Jacinda Ardern said she would not have used the word "embarrassing" to describe an MP's private health issues.
Political commentator Chris Trotter said Mr Bridges' actions in the wake of the investigation into who leaked his travel expenses had "the smell of death about it".
Now Mr Bridges has taken back his initial comments, expressing remorse at a press conference on Thursday.
"I regret it," he told media. "I think it's poor choice of words.
"As I clarified and I've said now a number of times, I was simply saying anyone, an MP or not, would prefer personal health issues dealt with in that way."
When asked why he chose to hold a press conference to express his regret, Mr Bridges said it was in the interests of transparency.
"It was important to be as open and transparent as we could while also respecting it was a personal health issue."