The European Commission, whose decision came after a year-long investigation, said profits earned by port authorities from economic activities must be taxed under normal corporate tax laws.

"The tax exemption does not pursue a clear objective of public interest, such as the promotion of mobility or multimodal transport," the EU competition enforcer said in a statement.

"The tax savings generated can be used by the port authorities to fund any type of activity or to subsidise the prices charged by the ports to customers, to the detriment of competitors and fair competition," it said.

Italy however will not have to recover corporate taxes that were not paid in the past because the corporate tax exemption existed before the EU Treaty came into force in Italy in 1958.

The Commission has issued similar orders to the Netherlands, Belgium and France in recent years.

(Reporting by Foo Yun Chee)