A car passes a street sign reading 'Austria' in the Italian village of Brenner on the Italian-Austrian border Thomson Reuters BRUSSELS (Reuters) - The European Commission is assessing whether plans by Austria to impose restrictions at its border with Italy breach EU rules on the free movement of people, following a complaint from Rome.

As part of efforts by several European nations to stem unprecedented migrant flows, Austria said last week it would introduce tougher controls at the Brenner Pass crossing from June 1 at the latest.

The Commission was analyzing if the measures, detailed by Austria on Friday in a letter to home affairs commissioner Dimitris Avramopoulos, were necessary and proportionate, a spokeswoman for the EU executive said in a statement.

In a letter sent to Avramopoulos last week, the Italian government had argued they were neither, as there were no signs this year of an increased northward flow of migrants at the Brenner Pass, the most important Alpine crossing for heavy goods traffic.

If Austria were found in breach of the Schengen rules on free movement, the Commission could start an infringement procedure, an EU official said, triggering possible financial sanctions.

(Reporting by Francesco Guarascio; editing by John Stonestreet)