BENTONVILLE, Arkansas, June 4 (Reuters News) - Walmart ( WMT ) has added Subway meals to its fast-delivery service, making meals from the sandwich chain available to customers through its app, as the retailer expands its e-commerce offerings in an increasingly competitive market.

Subway is Walmart's ( WMT ) largest in-store restaurant tenant, and the retailer said on Thursday that it plans to expand the fast-delivery service for the restaurant chain, which is already live in a few states, to about 1,400 stores by late summer.

The initiative could be the beginning of a larger effort.

"Subway is a great starting point ... but naturally for us, we want to make sure that any in-tenant location for our customers has the ability to have delivery via express," Tracy Poulliot, Walmart's ( WMT ) executive vice president of U.S. e-commerce and marketing, said on Thursday on the sidelines of its annual Associates Week event.

The retail bellwether is locked in fierce competition with e-commerce giant Amazon for delivery dominance, and has been testing drone delivery and AI-driven technology revamps to manage inventory, as demand grows among more affluent customers.

The company uses its over 4,600 stores to fulfill online deliveries, and it expanded its 30-minute delivery option for groceries and other items to about 33 cities earlier this year.

Executives said in May that the option was its fastest growing as consumers increasingly prefer convenience, and sales utilizing store-fulfilled delivery had more than doubled over the past two years, Walmart CFO John David Rainey told Wall Street analysts in May.

It also comes against the backdrop of an increasingly bifurcated economy in the United States, as lower-income households, once Walmart's ( WMT ) key target consumer, temper spending across the board.

Subway has been available in-store at Walmart's ( WMT ) supercenters since 2004. Fast food chains such as Taco Bell, McDonald's and Wendy's also have footprints at Walmart ( WMT ) stores, along with several regional operators such as Auntie Anne's.