|Italy has issued temporary residence permits to more than 20,000 migrants since Tunisia's revolt in January [EPA]
Tunisian migrants arriving in France from Italy will be sent back across the border if they cannot prove adequate financial resources, the French interior minister has said.
Claude Gueant said migrants could be returned to Italy under the rules of the Shengen Accords, which allows residents of EU countries to travel within the region without passports.
His comments are the latest in a row between Italy and France over people from the north African nation seeking refuge in Europe.
On Sunday France temporarily shut its border to trains from Italy carrying a group of about 60 mainly Tunisian migrants, leading to accusations from Rome that Paris was violating European principles.
However the European Commission said on Monday that France had acted within its rights.
Cecilia Malmstroem, the European home affairs commissioner, said French authorities had cited "public order reasons" for halting and inspecting the trains.
"Apparently they have the right to do this," she said, adding that France explained that the trains were stopped "very temporarily."
Italy has complained about being "left alone" by European Union partners to deal with thousands of mainly Tunisian migrants who have arrived on its southern island of Lampedusa in recent weeks, fleeing political turmoil in North Africa.
It has issued around 20,000 migrants with temporary permits allowing them to leave Italy to travel to other destinations in Europe, a policy which has been criticised by several of its partners, including France and Germany.
Some of the countries in the 27-nation EU are worried that offering shelter to too many migrants will encourage more to attempt illegal entry to Europe.
However on Monday Franco Frattini, the Italian foreign minister, said that despite their different handling of the Tunisian immigrants, France and Italy would "work together" to clear the cloud hanging over relations.
Earlier this month, the interior ministers of France and Germany agreed to set up joint patrols off the Tunisian coast to deter would-be migrants and Rome has also pledged assistance to Tunisia to try to halt the flow.