LOS ANGELES, Sept 8 (Reuters) - Federal law enforcement officials on Thursday were searching the offices of Solyndra, the U.S. solar startup that received millions of dollars in federal loan guarantees only to file for bankruptcy this week.

The search comes amid intensifying pressure on the Obama administration, which championed Solyndra as being at the forefront of solar technology when President Barack Obama visited the company's Fremont, California, facility in 2010.

"We are executing search warrants at Solyndra regarding a joint FBI and Department of Energy Office of Inspector General investigation," Julianne Sohn of the FBI said in an email.

DOE officials confirmed the search but declined to give any additional information.

Solyndra filed for Chapter 11 bankruptcy protection this week. The company received a $535 million loan guarantee from the federal government in 2009 and raised more than $700 million in venture capital funding in recent years.

The company said it could not bring down its costs fast enough to compete with cheaper Chinese rivals, and it is currently seeking a buyer.

Also on Thursday, House of Representatives Democrats Henry Waxman of the Energy and Commerce Committee and Diana DeGette of the Oversight and Investigations Subcommittee called on the subcommittee's chairman, Cliff Stearns, to invite Solyndra Chief Executive Brian Harrison to testify at a Sept. 14 hearing on the Solyndra loan guarantee.

In a letter to Stearns, Waxman and DeGette said Harrison met with the Energy and Commerce Committee less than two months ago and said at the time that Solyndra "was in a strong financial position and in no danger of failing."

Solyndra officials were not immediately available for comment.

The bankruptcy case is In re Solyndra LLC, U.S. Bankruptcy Court, District of Delaware, No. 11-12799.

For Solyndra: Bruce Grohsgal of Pachulski Stang Ziehl & Jones.

(Reporting by Dan Levine and Tim Gardner)

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