The Christchurch City Mission says Māori are suffering disproportionately in the aftermath of the earthquakes with housing shortages forcing two or three families to squeeze into one home and increased homelessness.
Its City Missioner said the housing needs of tāngata whenua were under-resourced.
Michael Gorman has praised the Government for the announcement that it would provide short-term accommodation alongside support services for up to 30 households at a time, but said while he was heartened the Government was taking a positive stance, it was a small one.
"It will only help a limited number of people. I ask myself the question, how bad does it get before people are helped when they're homeless?"
Mr Gorman believes the actual number of tāngata whenua affected by a lack of safe and affordable housing is not necessarily accurately represented.
"Māori help their whānau so they're taking them in until they can find accommodation, but so often people outstay their welcome because there isn't affordable accommodation in Christchurch and that creates stress.
"I think the numbers are masked by the fact that Māori hold family together, but the problem's exacerbated for them because so many people are being encouraged to come to Christchurch, but little care has been taken about where these new people live."
Mr Gorman said either host family members or the extended whānau forced to live with them were sleeping in their cars because of the strain and overcrowding. He said he heard other variations on that theme from the Mission's social work team.
The City Missioner believes the Māori cultural tradition of being hospitable and supporting whānau means they are more likely to suffer from overcrowding and homelessness.
"Māori are at further risk because of their strong support for whānau which means the problem is submerged.
"If there was less support the issue would be more noticeable. I think it's because of the absolute reluctance for them to say no to whānau members."
Michael Gorman said while the Government's programmes were great, more affordable houses needed to be built and more needed to be done.
Social Housing Minister Paula Bennett said in a statement: "The Government's Social Housing Reforms will create more social housing for people in need. We will be looking for different solutions for different people, depending on factors like age, disability, ethnicity, and so on.
"Our Social Housing Reforms are very well aligned with He Whare Āhuru He Oranga Tāngata - the Māori Housing Strategy, launched in 2014. The Christchurch short-term housing response will support around 240 families over the next two years, and will help relieve current housing pressures.
"If people are in need of assistance I encourage them to contact Work and Income to see what support they may be eligible for."