Reusable shopping bag with logo at Whole Foods Market grocery store in Dublin, California.

Amazon has expanded its grocery delivery service from its Whole Foods stores to more cities across the United States.

The service is now available in Milwaukee, Omaha, Detroit, Jacksonville, Madison, Orlando, St. Louis, Ann Arbor, Tampa and Tulsa as well as in more areas around New York City and Seattle.

In those places, shoppers can now get products from Whole Foods Market delivered to their homes through Amazon's Prime Now service. The delivery option, which was launched earlier this year, is now on offer in 48 cities.

The separate grocery pickup service, which was launched last month, is now being rolled-out to Fort Worth, Kennesaw, Richmond, Sacramento and Virginia Beach. Amazon said there are continued plans for expansion.

Customers can choose free pickup in as little as an hour on orders of $35 or more.