A Tainui kaumatua says the Waikato-Tainui iwi is challenging why wooden crates carrying Maori ancestral heads returned from France weren't opened during an official powhiri.
A welcoming ceremony for 20 toi moko was held on Friday on the marae of the national museum, Te Papa Tongarewa.
Tainui is currently the museum's iwi in residence, which means the marae follows the tribe's protocols.
An iwi elder, Te Wareta Taua, says he's disappointed the tribe's request for the lids to be removed wasn't approved.
He says the tikanga is followed according to the people who hold it and that clearly didn't happen in this case
Te Papa's co-leader Michelle Hippolite says museum staff seriously considered Tainui's request but had to decline it.
She says after consultation with its partner, Karanga Aotearoa Repatriation programme, it was agreed they had to consider the state of some of the heads and think about whether iwi would give their blessing for the world to see the toi moko.