Google Inc. is dipping its toe into the customer-service business as the world's largest Internet search company steps up competition with e-commerce giant Amazon.com Inc.

Google rolled out a new certification service called Google Trusted Stores on Thursday that helps shoppers see which online merchants ship quickly and reliably and which ones offer great customer service.

Google has been testing the free service with online retailers including Wayfair, Timbuk2 and Beau-coup. It is open to all U.S. merchants starting on Thursday.

Google offers up to $1,000 in what it calls "purchase protection" to shoppers who opt in to the program when making a purchase.

The company has a dedicated customer service team based at its Mountain View, California, headquarters to help resolve problems if shoppers are not getting anywhere with the merchant.

Google is also working on providing its own phone-based support for shoppers in the program, said Tom Fallows, an e-commerce veteran who is now group product manager at Google Shopping.

Fallows would not say how many Google employees are working in these new customer-service positions, but he said the business is "significantly overstaffed."

The move is unusual for Google, which is known for its tech-heavy, automated approach to business. About a year ago, the company started offering phone support for customers of its dominant AdWords online advertising service. But there are few, if any, other examples of such a hands-on, employee-centric approach to customer service, especially for consumer-facing businesses.

Google's commitment of such resources shows how important e-commerce is to the company. In general, the company benefits if more people search online for products and are confident enough to buy.

Scot Wingo, CEO of ChannelAdvisor, which helps merchants sell online, said the new Trusted Stores program may be a step toward Google building an online marketplace to rival the success of Amazon.com.

Amazon's third-party marketplace business, which lets other merchants sell through its web site, has grown rapidly in recent years and has been a big driver of Amazon's revenue and profit growth.

This success has encouraged more shoppers to search for products on Amazon.com, rather than going to Google — a potential threat to Google's search dominance online.