LOS ANGELES - Solar thermal company BrightSource Inc has dropped plans to build a solar power plant in the Mojave Desert, losing a battle with environmentalists and a U.S. senator who want to preserve the surrounding area.

Privately held BrightSource had applied with the U.S. Bureau of Land Management to build a 500-megawatt solar thermal power plant at the Broadwell Dry Lake area in California.

The project site is part of a larger area that Sen. Dianne Feinstein, a Democrat, wants to make into a national monument.

We have ceased all activity at the Broadwell site, BrightSource spokesman Keely Wachs told the Los Angeles Times.

The company started looking for alternative sites for the project in California and other states a few months ago, Wachs told the newspaper.

Solar thermal plants use solar heat to create steam that powers a turbine. They are typically much larger than those made up of photovoltaic solar panels, which turn sunlight into electricity.

BrightSource has picked up big contracts to deliver solar thermal power to California utilities Edison International Inc and PG&E Corp.

(Reporting by Laura Isensee; Editing by Braden Reddall and Richard