LONDON — Uber suffered a blow to its expansion plans in Europe on Tuesday after a senior adviser to the region’s highest court said that the ride-hailing service should have to abide by tough rules governing taxi services.

The recommendation, a nonbinding opinion by an advocate general for the Court of Justice of the European Union, adds to an array of challenges that Uber is facing worldwide. This year alone, the company has grappled with a sexual harassment scandal and the resignation last month of its chief executive, Travis Kalanick.

The case before the court hinged on whether Uber should be treated as a taxi service in France, and therefore be subject to rigorous safety and employment rules, or as a digital platform that merely connected independent drivers with passengers.

The French authorities brought criminal proceedings last year against the ride-hailing service for infringing a law that required any vehicle carrying passengers for a fee to be licensed as a taxi service and to have appropriate insurance.