San Francisco: The US Federal Trade Commission (FTC) has a message for Google Inc., Yahoo Inc. and other Internet companies: make sure online ads are clearly distinguished from regular Web search results to avoid misleading customers.

The FTC, updating recommendations in place for more than a decade, said search sites are displaying advertising more prominently on pages while doing less to highlight it. That has made it difficult for users to distinguish ads from results that aren’t backed by ad dollars, the FTC said. The regulator lamented a decline in compliance with guidelines from 2002.

In recent years, the features traditional search engines use to differentiate advertising from natural search results have become less noticeable to consumers, the FTC wrote in a sample letter posted on its website, dated 24 June. “We encourage you to review your websites or other methods of displaying search results, including your use of specialized search, and make any necessary adjustments to ensure you clearly and prominently disclose any advertising."

Search engines such as Google and Microsoft Corp.’s Bing have been seeking new ways to make money from advertising that’s tied to the keywords users type in when they’re scouting out information on the Web. Google has parlayed its lead in the Internet-search market to help it become the largest online advertiser in the world, according to EMarketer Inc.

Other companies receiving the FTC letter include AOL Inc. and 17 providers of search in areas such as shopping, travel and local business.

To distinguish ads from natural results, the FTC recommends that search engines use darker shading or more prominent borders to delineate marketing messages. The search engines also could use text labels that are clear and large enough for consumers to notice.

Failing to clearly and prominently distinguish advertising from natural search results could be a deceptive practice, the FTC said.

The guidelines follow an FTC decision to close a review of Google’s search business in January without taking action. The FTC voted 5-0 to end the investigation into whether Google unfairly skewed its search results to hobble competition.

Google said it would remove restrictions on use of its online search advertising platform and that it would offer companies the option of keeping their content out of Google’s search results. Bloomberg