NEW YORK — The mobile payment wars are heating up.

Wal-Mart Stores Inc., the world’s largest retailer, said it’s launching its own mobile payment system that will allow shoppers to pay with any major credit or debit card or its own store gift card through its existing smartphone app at the cash register.

It started testing the new payment feature Thursday at its stores in the Bentonville, Arkansas, area, where the retailer is based. It plans to launch the payment system called Walmart Pay in all 4,500-plus U.S. stores in early next year.

It’s part of Wal-Mart’s overall mobile strategy to making shopping easier and faster, but the launch is the latest salvo in the battle for mobile payments that’s in the early stages. Wal-Mart has moved into the field as Apple’s one-year-old tap-and-pay system is being expanded to other merchants like Best Buy and KFC and several months after Google launched the Android Pay mobile wallet app and Samsung came out with Samsung Pay. They’re all trying to get a piece of what could be a very lucrative business, but none of them has cracked the market so far.

The move signals that Walmart believes it’s best to build its own system to better serve its customers, even as it backs a retail industrywide mobile payment program that is in test phase.

Twenty-two million customers use the Wal-Mart app each month, and more than half of Wal-Mart’s online orders are now coming from a mobile device. This holiday season, Wal-Mart added new features like allowing online shoppers to check in once they get to the parking lot so they could have their online orders ready for pickup.

Wal-Mart executives said that after evaluating various mobile options, they found that they had different constraints, working only on certain devices or payment types.

Apple Pay requires iPhones. But Google’s own tap-and-pay services, Android Pay and Samsung’s Samsung Pay require Android phones.

However, Ashe and Daniel Eckert, Wal-Mart’s senior vice president of services, told reporters the system is designed to integrate with other payment applications like Apple Pay – if the retailer decides to include them.