"As a guardian of the treaties, the European Commission must ensure that European legislation is applied and respected and that is true for all member states, big or small," Viviane Reding said on Wednesday.
"In the case we are faced with today, we note that in our judicial analysis France did not correctly transpose the rules on free movement of European citizens and, as a result, she has robbed these citizens of essential procedural guarantees.
"This must be corrected and that is why the commission has acted firmly," Reding told reporters at her office in Brussels.
The European Commission also said on Wednesday that it was sending an official letter to France for not transposing EU laws on freedom of movement but that it had until October 15 to launch a clear timetable to show when and how it would.
"It is of the utmost importance that we make sure that the procedural and the substantive safeguards laid down in the 2004 directive on free movement of citizens is properly transposed in its entirety," Pia Ahrenkilder Hansen, spokeswoman for the European Commission president, said.
"The commission currently believes that France has not transposed the directive on free movement into its national laws in such a way as to make its implementation properly effective and transparent.
Therefore the commission has taken a decision here today to send an official notification letter," she added.
France welcomes decision
In its response, the French foreign ministry said it would provide Brussels with whatever other information it requests, and welcomed what it said was the Commission's acceptance that Paris'
expulsion policy is not racist.
"The Commission accepted France's assurances that the measures taken have neither the aim nor the effect of targeting a specific 'minority' and that French authorities apply EU law in a non-discriminatory fashion," it said.
"France notes no procedure has been undertaken in terms of the application of EU free movement rules and in particular in terms of measures taken to move on EU citizens detained during the evacuation of illegal camps.
"France will, of course, provide all necessary additional information, as it has already done up until now," the statement, issued by Bernard Valero, the foreign ministry spokesman, read.
Reding caused a storm when she attacked France for expelling Roma migrants this summer saying it
contravened the EU's rules of integration.
More than 8,000 Roma were expelled earlier this year, mostly to Romania and Bulgaria, and Reding expressed concern that they were singled out over other ethnic groups.
France denied the accusation but faced widespread criticism form EU parliamentarians, human rights groups and the Catholic Church.
An EU government can expel citizens of another EU state from its territory if they pose a risk to public security or are a burden on social assistance but measures have to be proportional to the risks and a government cannot target a particular ethnic group.
Nicolas Sarkozy, the French president, says the expulsions were part of a general crackdown on crime and vagrant camps which did not target the Roma specifically.
English Aljazeera
