WASHINGTON (AP) — A published report says federal regulators are preparing to issue subpoenas to Google and other companies as authorities gather information for a broad antitrust probe into the Internet search leader's business practices.

The Wall Street Journal reported Thursday that the Federal Trade Commission will issue subpoenas "within days," which would signal that it has opened a formal investigation.

The FTC is looking into whether Google abuses its dominance of Internet search to extend its influence into other lucrative online markets, such as mapping, comparison shopping and travel. Rivals complain that Google Inc., which handles two out of every three Internet searches in the U.S., manipulates its results to steer users to its own sites and services and bury links to competitors.

Google and the Federal Trade Commission refused to comment Thursday.

The European Commission and the Texas attorney general have already opened investigations into whether Google uses its enormous clout as a major gateway to the Internet to stifle competition online. The EU launched its investigation after competitors — U.K.-based price comparison site Foundem, French legal search engine ejustice.fr and Microsoft-owned shopping site Ciao — complained that their services were being buried in Google search results.

The Senate Judiciary Committee's antitrust subcommittee, too, is examining whether Google gives its own services favorable treatment in search results and is seeking to have either Google Chairman Eric Schmidt or Chief Executive Larry Page testify before the panel.

Google's rivals welcomed the news of an FTC probe, for which the agency has been laying the groundwork for months.

In a statement, FairSearch.org, a coalition of Internet travel companies including Expedia, Hotwire and Kayak, said, "Google's practices are deserving of full-scale investigations by U.S. antitrust authorities."

"Google engages in anti-competitive behavior across many vertical categories of search that harms consumers by restricting the ability of other companies to compete to put the best products and services in front of Internet users, who should be allowed to pick winners and losers online, not Google," the group said.

Gary Reback, a Silicon Valley lawyer who represents companies competing with Google in other online markets, stressed that any antitrust probe needs take a broad look not only at Google's so-called "organic" search results — which are ranked based on relevance — but also at the so-called "sponsored" results that advertisers pay for. He noted that these, too, tend to place Google's own services on the top.

In addition, because Google powers search functionality on many other Web sites, antitrust officials need to look at organic and sponsored search results on those sites as well, Reback said.

Although the FTC investigation would be the broadest federal inquiry into Google so far, the company is already in the crosshairs of U.S. regulators. In April, the FTC announced a landmark agreement with Google to settle charges that it deceived users and violated its own privacy policy when it launched a social networking service called Buzz last year. The settlement requires Google to adopt a comprehensive privacy program and submit to independent audits of that program every other year for the next 20 years.

Also in April, Justice Department officials extracted significant concessions from Google —many backed by the FairSearch coalition — in exchange for government approval to purchase airfare tracker ITA Software.

ITA was the latest in a series of big acquisitions by the search giant. Other big purchases include the 2007 acquisition of Internet advertising network DoubleClick and last year's purchase of mobile ad service AdMob, both of which were approved by the FTC without any conditions.

But to proceed with the ITA purchase, Google had to agree to accept ongoing federal monitoring to ensure it does not engage in anticompetitive behavior, which could include manipulation of search results.