Uber in Hungary in 2016. (Akos Stiller/Bloomberg News)

When it comes to challenging entrenched taxi companies, few have a bigger reputation than Uber. The ride-hailing company has successfully forced taxi drivers to compete with it in hundreds of markets around the world.

But now, a top official at the European Court of Justice has said Uber is more like the transportation companies it's sought to disrupt than the firm would have regulators believe.

Thursday's opinion from the court's advocate general finds that Uber is not the so-called information society service it claims to be, because the company's policies and app designs influence when, how and whether its independent drivers pick up passengers.

“Uber cannot be regarded as a mere intermediary between drivers and passengers,” the opinion reads.

The finding marks the latest in a string of setbacks for Uber, which faces the prospect of stricter regulation should a final court ruling concur with this week's nonbinding opinion. The case could also hold wider implications for the so-called “gig economy” in Europe as regulators grapple with changing patterns of commerce, employment and technology.

The advocate general's opinion is merely advisory in nature. But the opinion will be taken into consideration by the senior-most court in the European Union, which will issue its final ruling later this year.

Under the advocate general's interpretation of the law, Uber could be required to seek licenses and permits to operate in Barcelona, where the case first arose, according to a Thursday statement from the court.

The suit, filed by a local taxi association, saw Uber arguing that it is an “information society service,” a label that entitles the company to lighter regulation. But the advocate general said Uber does not meet a number of qualifying tests for the regulatory classification.

Uber said Thursday that it had seen the advocate general's opinion and would await the court's final ruling.

“Being considered a transportation company would not change the way we are regulated in most EU countries,” Uber said in a statement, “as that is already the situation today. It will, however, undermine the much needed reform of outdated laws which prevent millions of Europeans from accessing a reliable ride at the tap of a button.”

Uber is operating in 21 European countries.

In 2016, Uber launched its UberX service in Madrid after authorities there forced the company out roughly a year before. Unlike its counterpart in the United States, UberX drivers in Spain must be licensed professionals, not just private citizens with a car of their own.

Uber has faced legal battles in a number of other countries across the Atlantic, including Italy, the United Kingdom and Denmark — the last of which Uber said it would withdraw from after a law passed mandating the use of fare meters and other equipment.

Uber has had a tough start to the year, with multiple executive departures; a major intellectual property lawsuit between itself and Waymo, the self-driving car outfit owned by Alphabet, Google's parent company; defections by customers over links between chief executive Travis Kalanick and the Trump administration; and a federal probe into an internal application Uber used to circumvent regulatory officials in various cities.