(Reuters) - Alphabet's self-driving unit Waymo announced on Wednesday it plans to expand testing of its autonomous driving technology in over 10 new cities in 2025.

After testing the Waymo Driver in multiple cities, the company says the technology is adapting successfully to new environments, leading to the expansion.

In addition to ongoing trips to Truckee, Michigan's Upper Peninsula, Upstate New York and Tokyo, the expansion includes testing in San Diego and Las Vegas, with more cities yet to be announced.

"During these trips, we'll send a limited fleet of vehicles to each city, where trained human autonomous specialists will be behind the wheel at all times," a spokeswoman for Waymo said.

The testing will begin with manual driving through the densest and most complex parts of each city, including city centers and freeways.

Waymo plans to send less than 10 vehicles to each city, where they will be manually driven around for a couple of months, according to The Verge, which first reported the news.

In December, Waymo said it is expanding its autonomous ride-hailing services to Miami, Florida, adding another city to its operations as it seeks to gain an edge in an increasingly competitive market.

The firm is under intense scrutiny from safety regulators following multiple incidents involving autonomous driving technology.

Waymo said in October that it had closed a $5.6 billion funding round led by Google-parent Alphabet, as it looks to expand its autonomous ride-hailing service.