Google 's $3.1 billion (£1.56 billion) acquisition of online advertising superpower DoubleClick has ruffled a few feathers at Microsoft. The corporation's legal eagle Brad Smith has released a statement about the "serious competition and privacy concerns" Microsoft has over Google's proposed acquisition.

The buying of the online ad serving company is still 'proposed', since the deal won't conclude until later this year, but Microsoft's language clearly depicts the purchase as uncertain - in clear contrast to Google's statement.

"This proposed acquisition...gives the Google DoubleClick combination unprecedented control in the delivery of online advertising, and access to a huge amount of consumer information by tracking what customers do online, said the statement.

The statement also calls for action from the appropriate bodies to investigate the tie-up. "We think this merger deserves close scrutiny from regulatory authorities to ensure a competitive online advertising market."

And that's about it. David Drummond, Google's head of corporate development at Google, said he was sure regulators would approve the acquisition.

Google co-founder Sergey Brin said he was "excited" by the proposed purchase. "It has been our vision to make internet advertising better - less intrusive, more effective, and more useful," he said in a statement.

"Together with DoubleClick, Google will make the internet more efficient for end users, advertisers, and publishers."

To its credit, Microsoft doesn't go so far as to call for the merger to be stopped, instead it appears confident enough to leave this to the authorities. There's no doubt that a Google/DoubleClick merger would create serious issues for online advertising, where major players are relatively few.

Google is buying DoubleClick from private equity firm Hellman & Friedman plus other major investors. That company bought DoubleClick two years ago for $1.1 billion (£553m). The purchase will be Google's largest - dwarfing its £1.76bn acquisition of YouTube last year.