Nov 18 (Reuters) - Amazon's ( AMZN ) self-driving unit

Zoox started offering free rides to some early users in parts of

San Francisco, it said on Tuesday, as it steps up expansion amid

rising competition in the autonomous ride-hailing sector.

Tesla's launch of its robotaxi service this year

and accelerated expansion by Alphabet's Waymo have

renewed focus on commercializing autonomous vehicles, even as

high investments, tight regulations and federal investigations

have forced many to shut down.

Zoox is inviting people from its waitlist to try the

point-to-point service in San Francisco's South of Market,

Mission District and Design District neighborhoods, aiming to

refine the experience before scaling up.

The move comes just days after Waymo said it would start

offering robotaxi rides that use freeways across San Francisco,

Los Angeles and Phoenix. Waymo has been operating on San

Francisco streets for years and now runs a paid service across

several other U.S. cities.

Tesla launched its robotaxi service in Austin, Texas, this

year with safety monitors and has started a ride-hailing service

in the San Francisco Bay Area with drivers.

Zoox, with its purpose-built vehicle resembling a toaster

oven on wheels and without any manual controls such as a

steering wheel or pedals, began offering free robotaxi rides to

the public in and around the Las Vegas Strip in September.