The end of Europe's borderless Schengen area would cost the bloc more than 100 billion euros (110 billion dollars) in the long term, a French government-backed think tank said in a report released on Wednesday.
The report by France Strategie said that imposing border controls would cost France 1 to 2 billion euros in the short-term alone, depending on the intensity of the controls.
It attributed much of the cost to a decline in visitors from other European countries, as well as a smaller part to fewer cross-border workers and reduced movement of goods.
In the long term, it said imposing border controls would act effectively as a 3-per-cent tax on trade between countries in the region, based on anticipated losses.
It calculated the 100-billion-euro loss based on a 0.8-per-cent impact on Schengen area GDP.
Europe's free movement agreements have been strained with the influx of refugees and migrants, many fleeing conflict in Syria.
"This is yet another estimate on the cost of non-Schengen, which is ... even more dramatic than the figures that we have seen," said European Commission spokesman Margaritis Schinas.
"Although the estimates vary, I think there is only one certainty that emerges from all this: that the cost of non-Schengen will be very, very high."