An NZEI spokeswoman confirmed the union was intervening at the school.
"NZEI is helping facilitate further discussion at the school on the issue and the school is welcoming of this." Kelston Intermediate principal Phil Gordon said he had no idea some staff were unhappy with karakia in the classroom until contacted by the union representative.
A Ministry of Education official said state primary schools were required to be secular - but this didn't preclude teaching about religion.
A 2009 document produced by the Human Rights Commission advised teachers and principals to avoid leading pupils in prayer, the official added.
Gordon said he reassured the union representative the karakia was a cultural component of school life and an expression of beliefs that reflected the Kelston community.
"I guess what they might have been inquiring about is the presence of karakia, etc, within school so we talked about what we're doing is not a religious thing but a cultural thing."
Staff and pupils were free to abstain, he insisted. "I think perhaps there has been a mismatch in understanding."
Blessed tolerance
At the start of each school day the sound of a young voice reciting a Maori prayer, or karakia, rings out in every classroom at West Auckland's Rosebank School.
Children from the Avondale primary school's Maori bilingual unit lead pupils and staff in daily prayer, a tradition stretching back two decades in a school that is a melting pot of race and creed.
Principal Heather Bell says beginning the day this way brings a sense of grounding to the school and creates a sense of belonging.
Translated, the brief Maori prayer penned by the school's kaiarahi reo or Maori language assistant, says: "Lord look after us, guide us with your work today, in your holy name."
Bell says there has always been great community support for karakia in school, which also includes a lunchtime blessing for food and a prayer for safekeeping at the end of the day.
And if any child felt uncomfortable they were free not to join in reciting the lines.
As a principal with pupils from 31 nations the inclusion of karakia served to create a community where cultural diversity was celebrated, Bell said: "It's a great place to learn tolerance."