Battery manufacturer A123 Systems, a specialist in applying advanced battery tech at the large scales needed for vehicles and power grids, is suing Apple for allegedly poaching its engineers.
The case concerns five former employees of A123 currently employed by Apple, according to a court filing on Tuesday.
The company claims Apple was poaching its staff and "is currently developing a large scale battery division to compete in the very same field as A123".
Since June 2014, Apple has "embarked on an aggressive campaign to poach employees of A123 and to otherwise raid A123's business", it alleged.
Apple has not responded to the allegations in the complaint.
The filing comes amid growing rumours that Apple is ramping up its efforts to move into the electric car space.
According to The Wall Street Journal it has several hundred employees working on a secret project code-named "Titan" that included initial design work on a vehicle that resembles a minivan.
It is reported the company wants to take on Elon Musk's electric car company Tesla, which last week revealed it is about to unveil a home storage battery that could compete with the electricity companies as a power source.