National Maori Authority chair Matthew Tukaki is calling for the government to fund a "whakapapa project" to connect whanau to those buried in unmarked graves at Tokanui Cemetery.
The derelict Tokanui Hospital opened in 1912 and closed in 1998. In 2016, a memorial was unveiled to 457 psychiatric patients buried in unmarked graves there.
Matthew says the records of patients at Tokanui Hospital are lacking.
"In fact the records throughout the mental health system and the bursal system that ran for many, many decades in this country aren't that great."
He wants the government to fund a national project to ensure the people who are buried are accounted for.
"I would argue strongly there needs to be a whakapapa project as well and by that I mean linking those people from back then to their whanau today so their whanau can go back and connect with these people," he says.
Matthew says he has sat at the gravesites at Tokanui Cemetery and has sensed the discomfort for those lying there "still lost but not found".
Tokanui Hopital was built on Maori land taken under the Public Works Act in 1910 and was one of New Zealand's largest psychiatric institutions by the 1960s.
Maniapoto Maori Trust Board chair Keith Ikin told Stuff the loss of land was painful.
"The compulsory acquisition of the site caused Maniapoto much hurt, including the loss of a turangawaewae, the destruction of wahi tapu including ancestral burial sites, and the loss of resources and opportunities for economic development.
"This was by far the largest public works taking in the Maniapoto rohe and was strongly opposed by Maniapoto.
"The Crown has acknowledged that acquisition of the land was a Treaty breach."
Keith says no decisions have been made regarding the future use of the site.