Federal antitrust regulators have asked for more information about Google Inc's planned $12.5 billion acquisition of Motorola Mobility Holdings Inc.

In a filing with the U.S. Securities and Exchange Commission on Wednesday, Motorola said it received a request for additional information and documentary material from the U.S. Department of Justice's antitrust division.

Motorola said Google also received a similar request and repeated its expectation the deal would close by the end of 2011 or early 2012.

In a post on Google's official blog on Wednesday, Google Senior Vice President Dennis Woodside said the DOJ's second request was pretty routine and is something Google has faced in past deals such as its successful purchase of ITA Software.

We know that close scrutiny is part of the process and we've been talking to the U.S. Department of Justice over the past few weeks, Woodside said.

Google, whose free Android software is the top operating systems for Internet-enabled smartphones, announced in August it plans to acquire phone-maker Motorola.

The deal will give Google one of the mobile phone industry's largest patent libraries, as well as hardware manufacturing operations that will allow Google to develop its own line of smartphones.

The deal comes at a time when Google, the world's No.1 Internet search engine, has been under increasing regulatory scrutiny. The U.S. Federal Trade Commission and the European Union are both investigating Google's business practices. The company faces accusations it uses its clout in the search market to beat rivals as it moves into related businesses.

While this means we won't be closing right away, we're confident that the DOJ will conclude that the rapidly growing mobile ecosystem will remain highly competitive after this deal closes, Woodside said in the blog post on Wednesday.

(Reporting by Alexei Oreskovic; editing by Andre Grenon)

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