By Doug Palmer

WASHINGTON, Dec 30 (Reuters) - The U.S. Senate on Sunday approved prominent antitrust attorney William Baer to head the Justice Department's Antitrust Division 10 months after he was tapped by President Barack Obama.

The Senate voted 64-26 to approve Baer's nomination, which ran into problems with some Republicans because of secret information in an FBI background report.

Baer, an antitrust and white collar criminal defense attorney with the law firm Arnold & Porter LLP, has worked in the past for the U.S. Federal Trade Commission.

"Bill is a highly-skilled and well-respected antitrust lawyer who understands the importance of promoting competition in order for consumers to reap the benefits of lower prices and better quality products and services," Attorney General Eric Holder said in a statement welcoming the Senate vote.

The Justice Department's Antitrust Division, along with the FTC, reviews mergers to ensure they comply with antitrust law and prosecutes price-fixing and other antitrust violations.

Baer first joined FTC as a young attorney just out of law school and returned later to head its antitrust office.

At his confirmation hearing in July, Baer urged careful monitoring of powerful companies willing to flex their muscles to push aside rivals.

Obama nominated Baer in February to fill the post vacated by Christine Varney in mid-2011. James Wayland most recently served as acting head of the Antitrust Division, but left in November.

The Senate Judiciary Committee approved the nomination in September on a 12-5 vote, with the panel's top Republican, Mike Lee of Utah, joining the Democratic majority in support.

But Senator Charles Grassley, an Iowa Republican, said during that meeting he opposed Baer's nomination for reasons that he could not give in an open session.

Grassley and 25 other Republicans voted against Baer on Sunday while 14 Republicans voted for him.

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