BERLIN, July 4 (Reuters) -

Environmental authorities in the German state of Brandenburg, where Tesla has its gigafactory, have approved the U.S. electric vehicle maker's application to expand its Gruenheide plant, another hurdle cleared in the carmaker's growth plans.

The approval initially allows Tesla to set up an asphalted logistics area for new vehicles, as well as stairwells on its pressing plant and an access guard, the authorities said.

Tesla was not immediately available for comment.

The expansion is part of the Elon Musk-owned company's

plans to double the site's capacity

to 100 gigawatt hours of battery production and 1 million cars per year, setting it up to dominate Europe's EV market.

Environmentalists and local groups fear expanding the plant would endanger the region's water supply, as it is located in a drinking water protection area. (Reporting by Victoria Waldersee, Writing by Miranda Murray Editing by Madeline Chambers)