A general manager at Palmerston North Hospital told a thousand people on a WhatsApp channel that Indian nurses must stop using their language in any public space at work.
A patient had complained of being "disrespected", sparking the clampdown after an investigation last year.
A three-minute WhatsApp audio file from MidCentral Health head of HR Keyur Anjaria told members of the city's Malayli community that for nurses anywhere in hospital public spaces, "talking in the local dialect is not allowed".
This follows an incident where Waikato public hospital told nurses not to speak to patients in any language other than English last week, with a similar directive issued at Christchurch's Intensive Care Unit in April.
Labour leader Chris Hipkins told Morning Report such directives were "discriminatory and wrong".
Having different language capabilities was a benefit for the health system, he said.
"Patients should be communicated with in the language that they can best understand.
"Two Filipino nurses communicating with each other in the language that they best understand, as long as it's not affecting patient care and it's not causing confusion for patients, I don't see a problem with it."
Health NZ chief executive Margie Apa told Morning Report that there isn't an official policy on languages spoken in clinical settings.
"If it's clinically safe to speak in another language then that's ok, and I back our staff to use their judgement.
"English is the appropriate language to use if it helps everybody be clear about what's going on, understand what's happening in care, but importantly participate in that care," she said.
"People come to work to be themselves and we encourage that. But in clinical settings, it is important to have clear communication."
Health New Zealand initially defended the Waikato Hospital directive, telling RNZ that exclusive use of English in all clinical settings was safer, before the Health Minister and Health NZ's chief executive stepped in to reverse the clampdown.
Anjaria undertook two investigations at MidCentral Health in late 2023, the first sparked by a patient who complained of feeling "quite disrespected and excluded from the conversation" by two nurses speaking the Malayalam language.
Malayalam is a language spoken in the Indian state of Kerala.
The second investigation, which looked at a complaint from a charge nurse, found "the majority of the communication that is happening between Indian staff [on a ward] is in their local dialect".
"Now this is starting to raise some issues across Mid-Central and a lot of charge nurses are unsure of how to handle it," Anjara said in the clip.
This also applied in resthomes.
A Malayli community member told RNZ they did not work for MidCentral Health, but they and their friends who did work there felt profound anxiety and trauma when they heard the clip.
"It is unreasonable to restrict the use of one's mother tongue even during staff break times," the person said by email.
"The clip has been circulated widely, and it has left many members of our community, particularly the overseas nurses, feeling undervalued and threatened by the statement made by a high-ranking hospital management official."
Any directive should have been a matter of internal communication directed at hospital staff, not in a "WhatsApp group [that] has members from all over the world".
"What is particularly troubling is the perception that this directive may have been specifically aimed at staff from the Malayali community," as this felt discriminatory, they said.
Saju Cherian - a nurse who is in the Kerela Association - said there was a mixed response, with some supporting the message.
Cherian said he personally thought it was inappropriate, and he felt that all cultures and languages should be respected.
He was worried that this may not have been a one-off incident.
"It's very concerning that they decided to deal with it in this way, I don't know how in other issues - if this is the style of dealing with issues like this - what else could have happened... this person or other managers could have done?"
Anjaria asked in the WhatsApp clip if the Palmerston North Malayali Network, associated with the Kerela Association of Palmerston North, could "please pass this voice note to your members".
"Just remind them that they should only talk in English, preferably, unless they know how to speak sign language or Māori. They should talk only in English when they're in a public setting.
"This matter has started picking up some speed."
In a statement, a Te Whatu Ora spokesperson said the organisation was "looking into this situation internally".
The Waikato Hospital memo - sent on Friday - said nurses needed reminding about using English, to cut down the chance of "missed care". Health NZ told RNZ on Monday the memo was "to help reduce confusion" and nurses could talk to patients in wards in other languages.
In the case in Christchurch, concerns and complaints had been made about languages being used on the clinical floor in ICU.
A memo asked all staff to speak English, and not their native language in front of patients and their families, or to their colleagues.
Health Minister Shane Reti said yesterday that English was the base language at Health NZ, but there had been no directive from the government.
"Nurses who want to speak their first language to each other and / or to patients where they feel it's clinically safe and apply their clinical judgement, so they should be able to."
Health NZ chief executive Margie Apa said she could see how these directives may have caused concern.
She put out another memo, saying where it was clinically safe and appropriate for patients and working in teams, staff should exercise their professional judgement on what language to use.
International nurse numbers rose to make up almost 45 percent of the workforce in June. In the previous three months, almost 3000 from the UK and Ireland flowed into the country, with 700 from the Middle East and a few hundred from India and the Philippines.
Cherian - who works as a mental health nurse in Palmerston North Hospital - said he experienced racism from patients on a weekly basis.
"It's racial slurs, it's like saying, go back to your country, go back to where you come from, sometimes calling names, and sometimes saying you don't belong to this country, you don't understand things," he said.
Cherian said he had also felt indirect discrimination from other staff members, about once in a month.
Cherian, who's on the board of the nurses union, said the systemic discrimination was also reflected in unequal job opportunities, having heard that nurses from ethnic minorities were finding it harder to move up the professional ladder.
Professor of translation and interpreting Ineke Crezee said the language memos were a lurch back in time.
"What does this do for the Right to Effective Communication, which is Right 5 in the Health and Disability Commissioner Code?" she asked.
"My career has been dedicated to training healthcare interpreters, however these are not always available and not always used - it is an additional cost to the ward.
"In the absence of interpreters, is it not wonderful that patients can communicate their healthcare needs to the nurses looking after them in their own language and fully understand instructions?"
But other feedback by emailers to RNZ supported the push for communication in English, on safety grounds.