By David Thomas

Jan 21 (Reuters) - David Bernhardt, a former energy lobbyist who served as the Secretary of the U.S. Interior Department during the first administration of President Donald Trump, has rejoined U.S. law and lobbying firm Brownstein Hyatt Farber Schreck in Washington, the firm said on Tuesday.

Bernhardt previously served as the leader of the firm’s natural resources department before he left in 2016 to work on the Trump transition team and then in the U.S. Interior Department.

Bernhardt most recently has focused on nonprofit work, according to Brownstein's press release. He currently is identified as chair of the Center for American Freedom at the America First Policy Institute, a Trump-aligned think tank, on the organization's website.

He became the acting interior secretary in December 2018 when his predecessor, Ryan Zinke, resigned after facing ethics investigations. He was confirmed by the U.S. Senate in a 56 to 41 vote.

Bernhardt did not immediately respond to a request for comment, including on whether he plans to register as a lobbyist again.

Bernhardt's past lobbying clients have included Noble Energy Inc, Rosemont Copper Co, Sempra Energy, and California's Westlands Water District, among others.

Bernhardt previously worked in the Interior Department during the Republican George W. Bush administration.

The Interior Department oversees more than one-fifth of the U.S. land surface from Alaska to the Gulf of Mexico. The department played a central role in Trump's policy of boosting domestic crude oil, natural gas and coal production during his first term.

Brownstein's clients have included NEOM , Saudi Arabia's $500 billion flagship high-tech development on the Red Sea, as well as Apollo Global Management, Exxon Mobil and Purdue Pharma.

(Reporting by David Thomas)

((D.Thomas@thomsonreuters.com;))