SAN FRANCISCO, Aug. 16 (Xinhua) -- A California-based autonomous driving startup Nuro said Thursday it has begun pilot driverless grocery delivery service in Arizona state in partnership with Kroger, the largest U.S. operator of traditional supermarkets.

"Grocery delivery with Nuro self-driving vehicles starts today! Our pilot with @kroger in Scottsdale, AZ is now accepting orders," Nuro tweeted.

Nuro said its self-driving fleet of Toyota Prius vehicles will be on the road delivering groceries to customers of the Kroger-owned Fry's Food Store in Scottsdale, a desert city in Arizona east of state capital Phoenix.

Customers can place orders via Fry's website or mobile app and Grocery orders can be scheduled for same-day or next-day delivery.

"We're excited to launch our autonomous vehicle delivery pilot with Fry's in Scottsdale," said Kroger Chief Digital Officer Yael Cosset.

"Kroger wants to bring more customers the convenience of affordable grocery delivery, and our pilot with Nuro will help us test and learn to understand customer acceptance of autonomous vehicles in our seamless offering," he added.

The pilot driverless delivery program aims to cut the high cost of "last-mile" deliveries to customer doorsteps in what Nuro advocates as its mission to "accelerate the benefits of robotics for everyday life."

Nuro is a new startup founded in 2016 by two ex-Google employees who were Principal Engineers at Google's self-driving car project, which is now a Google sister self-driving firm Waymo.

At the first stage of the pilot program, the autonomous grocery delivery car will have a safety human driver behind the wheel to override autonomous systems in the event of an error or emergency.

Nuro plans to replace Prius cars with its custom-built R1 driverless delivery vehicles later this fall.

The R1 vehicles that have no seats are currently being tested at Nuro's headquarters in California.

Earlier this summer, the U.S. grocery giant Kroger and Nuro announced a partnership to begin testing grocery delivery using Nuro's robots.

"Arizona is home to some of the most innovative autonomous vehicle testing," said Nuro co-founder Dave Ferguson.