Customers shopping for books, DVDs, clothing and toys on Internet powerhouse Amazon.com (AMZN) can now add groceries like canned tuna to their shopping cart.

The Seattle-based company, which began testing the grocery site on May 25, is offering 15,000 nonperishable items, about half in organic products. The offerings range from Kellogg's Special K cereal to StarKist's canned tuna and Tide detergent.

"This is so natural for us," said Tracy Ogden, spokeswoman for Amazon.com Inc. "This is for the busy parents, suburban and urban, who want to load up on diapers and pasta."

Customers who order $25 or more or are members of the "Amazon Prime" free shipping program can get free standard shipping. Shoppers can buy items in single-serving portions, but many offerings are in bundle capacity, Ogden said.

In October 2003, Amazon.com launched a gourmet food section but it teamed up with such third party merchants as Dean & DeLuca. With the launch of the grocery online store, Amazon owns the inventory.

Last year, Amazon.com expanded into beauty products.

The expansion into groceries marks a big move for the Internet retailer, which is expected to compete with New York-based FreshDirect.com and Peapod LLC, both of which are flourishing.

Such a resurgence in online food retailing follows the spectacular crashes of such online food retailers as Webvan.com during the dot.com bust. That left a black mark in the industry.

Amazon.com's shares rose $1.28, or 3.80 percent to $34.96 on the Nasdaq, where it added another 4 cents to $35 in after-hours trading.