Border police on Thursday sent back to Italy some 15 migrants who had entered France from the northwestern coastal town of Ventimiglia. Police checks were also stepped up at the central stations in the southern French cities of Nice and Cannes and at other stations on the border with Italy.
A day earlier, France returned some 170 migrants to Ventimiglia, claiming that under European law they must stay in the European country in which they arrived while their asylum claims are processed.
Controls have also been stepped up at Austrian and Swiss borders with Italy, and asylum-seekers unable to leave Italy have been sleeping rough at train stations in Milan and Rome as well in Ventimiglia.
Most of the migrants stranded in Ventimiglia are being given shelter at the station, but a group of around 100 migrants have been camped out on rocks by the sea for six days demanding to be allowed into France.
Italy has registered 60,000 migrants that have landed on its territory since the start of the year and is pushing for a change to EU rules to allow their redistribution across the bloc - a move resisted by many member states including France.
EU heads of state and government are due to decide whether to back the proposed migrant quotas at a summit later this month.