The French Immigration Ministry is to fingerprint Roma (Gypsies) who get financial aid after being deported.
From Friday, biometric records will be created on Roma and other foreigners who receive up to 300 euros (£259; $409) after they leave France.
Most of them are repatriated to Bulgaria and Romania.
Authorities say some expelled Roma make return trips to France to benefit several times from the humanitarian aid they get for going home.
In 2009 more than 15,200 return aid payments were made to immigrants, mostly Roma, who were expelled from France.
The French government classes the majority as "volunteers", who are given a cash payment of 300 euros per adult or 150 euros for each child.
The expulsion fund cost the French government 9m euros last year.
BBC News
