In its blog post on Wednesday, Internet search giant Google said that its proposed $750-million acquisition of mobile advertising provider AdMob might take time to close, since the US Federal Trade Commission sent Google a “second request” this week, seeking additional information about the Google-AdMob deal.

Noting that the antitrust regulators intend reviewing the AdMob acquisition’s competitive impact on the embryonic mobile advertising market, Google Product Manager Paul Feng said in a blog post: “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.”

AdMob is a privately-held firm focusing on technology for serving graphical, display ads on mobile phones. The firm, via its network, enables advertisers to place display ads on mobile Web sites as well as directly within dedicated smartphone applications.

The acquisition plan for AdMob was announced in November by Google, which said that the AdMob would slot in perfectly with Google’s forceful presence in potentially gainful mobile search ads arena.

While announcing its takeover of AdMob last month, Google had said that the deal would likely come through in a few months. However, now stating that the deal will not close “right way,” Feng said that the closer FTC review is a likely upshot of Google’s dominant search market position.