SALEM, N.H. — Walmart on Wednesday unveiled its latest weapon in the battle against Amazon and Kroger for shoppers' food spending: a grocery-picking robot.

The machine, part of a system called Alphabot, operates in a 20,000 square-foot facility that Walmart built onto one of its stores in Salem, New Hampshire. The company plans to build similar facilities onto stores in Mustang, Oklahoma and Burbank, California this year.

Automated grocery systems like Alphabot are estimated to pick and pack orders as much as 10 times faster than a human. This could enable Walmart to rapidly expand its capacity for orders as demand for online grocery services grows.

"Demand for this business continues to grow," Tom Ward, senior vice president of central operations for Walmart, said of the company's online grocery business. "Systems like [Alphabot] allow us to scale enormously."

Alphabot involves an elaborate shelving system. Business Insider/Hayley Peterson

Inside the Alphabot facility on Wednesday, about 30 small, cubic robots wheeled around inside a giant shelving system, picking and packing grocery orders from a selection of about 4,500 items.

The system is operating now at a fraction of its future capacity. It was built to hold 20,000 SKUs and will add about 20 more of the grocery-picking robots in the future, said John Lert, the CEO of Alert Innovation, the company that built the automated system for Walmart.

The Alphabot's robots move vertically and horizontally, transferring thousands of blue bins around the shelving system as they pack orders for delivery or pickup.

When customers arrive at the Walmart store to pick up their orders, workers can retrieve their items from one of several stations attached to the Alphabot shelving system. At these stations, workers input a grocery order number and the system spits out bins belonging to that order.

Inside the bins are shoppers' groceries, all bagged and ready to go.

This small, cubic robot picks groceries. Walmart

For now, Walmart workers continue to pick and pack fresh produce such as apples and carrots for online orders at the Salem store, while the Aphabot system fulfills everything else, including cereal and canned soup.

Ward said Walmart is exploring systems that automate the fresh-produce picking process, as well.

In addition to picking orders faster and more accurately than a human, the Alphabot system could help alleviate a key problem: crowding in Walmart's grocery aisles as workers pick and pack a growing number of online orders.

Former Walmart US CEO Greg Foran discussed this problem at a UBS conference last year.

The Alphabot facility is 20,000 square feet. Business Insider/Hayley Peterson

"We got into this discussion actually on Monday at our office meeting where one of our senior folks was saying, 'I hate shopping in the store on Sunday trying to get up and down the aisles," he said.

"We're looking at what happens when you start to cap this out and is there some automation that we can put in, which may be built onto the store ... that will allow us to not disadvantage our most profitable customer which is the one who drives to the store and does all the work themselves," he said.

Brian Roth, senior manager of pickup automation and digital operations for Walmart US, said Alphabot will be transformative for the company.

"By assembling and delivering orders to associates, Alphabot is streamlining the order process, allowing associates to do their jobs with greater speed and efficiency," Roth said in a statement. "Ultimately, this will lower dispense times, increase accuracy and improve the entirety of online grocery. And it will help free associates to focus on service and selling, while the technology handles the more mundane, repeatable tasks."