March 19 (Reuters) - Amazon.com's ( AMZN ) self-driving

unit, Zoox, has recalled 258 vehicles due to issues with its

automated driving system (ADS) that could cause unexpected hard

braking, the company said on Wednesday.

The recall affects vehicles equipped with ADS software

versions released before November 5, according to a report Zoox

filed with the National Highway Traffic Safety Administration

last week.

The California-based company said it has addressed the issue

by updating the ADS software on affected vehicles.

While the company has not publicly disclosed the number of

vehicles on the road, it has ramped up testing over the past

year.

Last June, the company announced plans to

begin testing its autonomous vehicles in two new cities.

Self-driving vehicle companies, including General

Motors' ( GM ) Cruise and Google-owned Waymo, are

under heightened scrutiny following a 2023 incident where a

pedestrian was seriously injured by a Cruise vehicle.

Last year, Waymo

recalled

more than 670 self-driving vehicles after one of its

driverless vehicles struck a wooden utility pole in Phoenix,

Arizona.