A fleet of Amazon 'Scout' delivery robots will roam the streets of Southern California as part of the firm's largest trial of automated 'last mile' delivery.

Last-mile delivery is the last stage of getting a package from a warehouse to your door, traditionally completed by a van or truck.

Retailers and courier firms are racing to automate this process through the use of drones, either by land or by air.

Amazon's latest roll-out follows a successful trial conducted in a small neighbourhood in Washington state earlier this year.

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Each Scout robot is a squat, bright blue device that gets around on six wheels. The all-electric devices are about the size of a small cooler and can deliver packages autonomously

WHAT IS AN AMAZON SCOUT? Each Amazon Scout robot is a squat, bright blue device that gets around on six wheels. The battery-powered devices are about the size of a small cooler and can deliver packages autonomously. Amazon says the robots 'roll along sidewalks at a walking pace' so they don't run into pedestrians. Each drone has a hatch that users can open to remove their package. Advertisement

'While in the Pacific Northwest, Scout has experienced all of the region’s weather—from the expected rain shower, to the infrequent sun, and even the biggest snowstorm the area’s seen in the last decade,' said Sean Scott, vice president of Amazon Scout, in a written statement.

'It’s now time for Scout to experience a little more sunshine.

'I’m thrilled to report that, starting today, Scout will begin to deliver packages to customers in Southern California.'

A small number of Amazon Scout devices will deliver packages Monday through Friday, during daylight hours.

Customers in the Irvine area will order as they normally would and their Amazon packages will be delivered either by traditional courier or by an Amazon Scout.

Amazon is also developing airborne delivery drones (pictured) as well as using using robots in its warehouses to handle menial tasks

Amazon previously tested the technology in a neighbourhood in Snohomish County, Washington.

Six 'Scout' robots were sent out to deliver packages to customers on weekdays in the area.

During the trial, the devices safely and autonomously navigated the many obstacles you find in residential neighbourhoods, including trashcans, skateboards, lawn chairs and more.

About the trial, Mr Scott added: 'One of our favorite parts of this journey so far has been witnessing how excited customers are when they see the delivery device for the first time and how they’ve welcomed Scout into their neighborhood.

'In the span of a week, our Ambassadors witnessed a child ask her dad for a Scout for Christmas, and another customer ask if he could hitch his two dachshunds to Scout and use it as a dog walker.

'While the intent of our "adora-bots" is and will remain delivery, we couldn’t help but chuckle at these reactions. We have a lot of pride packed inside these cooler-sized devices and love to see such a positive reaction from the community.'

Amazon is also developing airborne delivery drones as well as using using robots in its warehouses to handle menial tasks.