The Wall Street Journal has picked up on news that the US Federal Trade Commission has taken an interest in Google's acquisition of mobile advertising giant AdMob.

The investigation is purely procedural at the moment, according to Google, which stated, "We don't see any regulatory concerns with this deal, but closer scrutiny has been one consequence of our success. On that basis, we wouldn't be surprised if there were some regulatory review before the deal closes."

The growing success of AdMob has garnered a lot of attention lately, especially since the company bought up mobile ad mediation provider AdWhirl in a controversial move in August.

This fast and successful growth, which is directly linked to Android, prompted a $750 million offer from the internet search giant. Given Google's size and dominance of online advertising, it does seem likely that the FTC would be interested in vetting any new acquisitions for anti-trust issues as a matter of course.