United States ride-hailing giant Uber is expanding its global robotaxi operations through a partnership with autonomous driving company Pony.ai.

The companies announced Friday that they plan to deploy 2,000 Pony.ai self-driving taxis across Europe while also extending their partnership to the Middle East.

Uber and Pony.ai launched a commercial robotaxi service in Zagreb, Croatia, in late March, describing it as the first of its kind in Europe.

Under the latest agreement, the companies will introduce robotaxis in four additional European cities.

They did not disclose the cities or provide a specific timeline for the rollout.

A sufficiently large vehicle fleet is key to scaling commercial robotaxi services. More vehicles allow operators to gather greater volumes of data, strengthen safety assessments for regulators and improve operational efficiency. Wider vehicle availability could also drive greater consumer adoption.

Alphabet-backed robotaxi operator Waymo remains the global leader, with about 5,000 vehicles, most of them operating in the United States.

The company is currently testing its service in London and reportedly established new entities in four major EU economies in June.