May 29 (Reuters) - Amazon.com's ( AMZN ) self-driving

unit Zoox has issued a second software recall this month to

improve how its vehicles track nearby pedestrians and prevent

movement when someone is close, following a crash in San

Francisco earlier this month.

The recall covers 270 vehicles equipped with its Automated

Driving Systems software, which had versions released prior to

May 21, Zoox said in a report with the National Highway Traffic

Safety Administration on Thursday. Zoox has updated the

software.

On May 8, an unoccupied Zoox robotaxi was struck by an

electric scooter while turning at low speed at a San Francisco

intersection, the company said last week.

The rider sustained minor injuries and fell next to the

vehicle, which continued turning and then stopped without making

further contact, it said.

Earlier this month, Zoox had issued a software recall for

270 driverless vehicles after an unoccupied robotaxi was

involved in an April 8 crash with a passenger car in Las Vegas.

In April, NHTSA closed a probe into 258 Zoox vehicles over a

braking issue after the company issued a recall to update their

software.