The French Polynesian government says it expects a massive influx of people, should New Caledonia opt for independence from France next month.
A third and final referendum is due to be held on 12 December on whether New Caledonia should assume full sovereignty.
New Caledonia votes a second time on independence from France Photo: AFP or licensors
The government-commissioned study has found that a yes vote will unleash a wave of migrants, including French Polynesians who over time had moved to New Caledonia.
In a speech to the assembly, President Edouard Fritch said also many French people would be arriving from Noumea, which risks fuelling property prices in Tahiti and Moorea.
He says there is no need to have a psychosis about an invasion but to keep an eye our for developments.
Mr Fritch also says he doesn't want to take sides in New Caledonia's independence debate but hopes whatever decision is made, there will be a way for people there to live together.
Both French Polynesia and New Caledonia are on the UN decolonisation list.
While France has engaged with the UN and organised New Caledonia's referendums, Paris refuses to acknowledge French Polynesia's listing.
To date France has ignored all calls for a referendum made by either pro- or anti-independence politicians in French Polynesia.