Several internal TVNZ sources said staff were upset they were not consulted about him replacing previous host John Campbell and that he did not undergo a rigorous hiring process.
It is understood TVNZ staff were aware Santamaria was coming to the broadcaster before Campbell had officially announced he was moving on from the Breakfast role.
One source said they believed TVNZ Head of News and Current Affairs Paul Yurisich had "ruffled feathers" with longstanding staff since arriving at TVNZ in late 2020.
Broadcasting and Media Minister Kris Faafoi said through a spokesperson that he was made aware of the situation at TVNZ through the "no surprises" principle - in which ministers are kept informed about sensitive matters which may become public.
The spokesperson said he had been assured by TVNZ that the situation was being managed appropriately "with the correct support in place for those involved".
No further comment would be given because it was an internal staffing matter, they said.
Santamaria was absent from the Breakfast show for the past week, and TVNZ initially explained on Friday that he was dealing with a "family emergency". A day later, the broadcaster said in a statement that he was dealing with a "personal matter".
A TVNZ spokeswoman declined to answer questions today about Santamaria's appointment, whether there had been any complaints against him, or why his departure was initially described as a "family emergency", saying that TVNZ did not comment publicly on individual employment matters.
Auckland employment lawyer Michael O'Brien said there was generally no strict obligation on companies or entities to consult widely with existing staff when hiring new employees - and privacy and confidentiality issues could also prohibit this.
"However, existing employees often can be a useful source of reconnaissance and background checking," he said.
Santamaria quit the high-profile role just 31 days after his first day on air.
An email went out to TVNZ staff yesterday at 2.45pm from Yurisich to say he had accepted the resignation.
In a statement yesterday, the network told the Herald, "TVNZ has accepted the resignation of Breakfast presenter Kamahl Santamaria. Kamahl has been on leave the last week, while he dealt with a personal matter which required his full attention, and he has now advised that he wishes to take an extended break with his family.
"Kamahl is focused on his family at this time, and we ask that everyone respects their wish for privacy."
On last night's 6pm news bulletin, a TVNZ reporter said Santamaria had told viewers he was going to Wellington to present after the Budget from the capital, but that never happened. Since then, Santamaria had been off air and viewers and staff hadn't been told why.
The reporter pointed out that what was earlier referred to as a family emergency was now being described as a personal matter.
Yesterday the Herald reported that the new star had not been seen on Breakfast for nine days. Santamaria was last seen on the show on May 18.
When contacted by the Herald for comment on Friday, TVNZ issued a short statement revealing Santamaria is currently navigating a "family emergency".
They added: "The matter is private to Kamahl and we are respecting he and his family's privacy."
TVNZ is yet to confirm who will fill in for Santamaria on the morning news show.
Santamaria, an Auckland-born journalist, started his career as a sports reporter for Newshub before leaving New Zealand to pursue other ventures.
