Walmart's mobile payments service can now be used for transactions at all of the grocer's US stores, following a technology upgrade over the last few days.

The in-house payments tool, which is available through the Walmart mobile app and works with any iOS or Android device, can now be used by customers at any checkout lane in the supermarket's 4,600+ stores across the country. Shoppers can align any credit, debit, pre-paid or Walmart gift card with the payments platform.

Daniel Eckert, senior vice president for services at Walmart US, suggested the company will be launching an array of further retail innovations for its customers in the months ahead. The business's mobile app already allows users to refill their pharmacy prescriptions, build a gift registry, find where an item is located in store and shop the full range on Walmart.com.

"Walmart Pay is just the beginning," Eckert commented.

"We're building deeper relationships with our customers across our ecosystem and are looking forward to delivering new tools like Walmart Pay that allow them to use the Walmart App as their remote control for a faster, more convenient shopping experience."

Walmart said there was a 45% uplift in the number of shoppers using Walmart Pay in the last week, as the full set of store locations were added to the company's mobile payments network. Walmart is arguably the most high profile US retailer to withhold from accepting Apple Pay in its stores, with the retailer confident it can better serve its customers by encouraging them to use the in-house system.

There is nothing preventing Walmart from offering other mobile payment services alongside Walmart Pay, but the company's preferred route at present is to encourage customers to access and use its own tech ecosystem when in a store.