Antitrust officials with the U.S. Federal Trade Commission have asked Internet giant Google for more information about its planned acquisition of mobile advertising provider AdMob, indicating the agency is taking a closer look at the deal. Google acknowledged in a blog post the request is the second time the agency has come looking for additional information, and that the company has been working with the FTC over the last few weeks.

In November, Google announced a plan to acquire AdMob for some $750 million in an all-stock deal. Google plans to leverage AdMob’s services and technology to offer advertising both for mobile services as well as within mobile applications for platforms like the iPhone, BlackBerry, and (of course) Google’s own Android platform. Industry watchers see the FTC’s increased scrutiny of the deal as a direct result of Google’s dominance of the Internet search advertising market, as well as Google overall success in recent years. However, the additional review may mean it takes longer for a deal to close, potentially giving competitors more time to respond.

Google has said it does not expect any regulatory issues with the AdMob acquisition.

For the record, here’s Google’s complete blog post:

Wednesday, December 23, 2009 Posted by Paul Feng, Group Product Manager

Since we announced our plans to acquire AdMob, we’ve been excited about the positive reaction — particularly from advertisers and publishers who have told us that they’re enthusiastic about the possibilities for how the combination of AdMob and Google can improve the effectiveness of mobile display advertising.

As we said when we announced the deal, we don’t see any regulatory issues with this deal, because the rapidly growing mobile advertising space is highly competitive with more than a dozen mobile ad networks.

That said, we know that closer scrutiny has been one consequence of Google’s success, and we’ve been talking to the U.S. Federal Trade Commission over the past few weeks. This week we received what’s called a “second request,” which means that the FTC is asking for more information so that they can continue to review the deal.

While this means we won’t be closing right away, we’re confident that the FTC will conclude that the rapidly growing mobile advertising space will remain highly competitive after this deal closes. And we’ll be working closely and cooperatively with them as they continue their review.