The "Facts about Google's acquisition of AdMob" page Google established in November of last year apparently hasn't satisfied the Federal Trade Commission's curiosity.  A fresh report indicates that the FTC has stepped up its investigation of the deal by seeking sworn declarations from third parties.

This isn't a good sign for Google.  Todd Shields and Dina Bass heard about the FTC's move from "people with direct knowledge of the matter," so the affair appears to have developed beyond rumor stage.

Also, after talking to Stephen Calkins, a professor of law who used to serve as General Counsel of the FTC, Shields and Bass reported that the FTC tends to seek declarations "'when they think there is some significant chance' the agency will ask a court to block a merger, or seek to modify a deal."

Google's been running into more and more antitrust trouble as of late.  From the problems with its book digitization project to a European Commission probe, the search giant's been held up on several fronts.  It wouldn't be surprising if something - such as this AdMob deal - becomes a breaking point.

Still, asking for sworn declarations isn't the same thing as strongly objecting.  It remains possible the FTC will give Google's acquisition of AdMob a green light.