WASHINGTON, June 21 (Reuters) - The U.S. Supreme Court on Monday rejected a bid by an Amarin Corp PLC subsidiary to revive patents on its heart drug Vascepa in a legal battle against generic drugmakers Hikma Pharmaceuticals PLC and Dr. Reddy's Laboratories Ltd.

The justices declined to hear Dublin-based Amarin Pharma's appeal of a lower court ruling that affirmed that the patents were invalid following a challenge by Hikma and Dr. Reddy's. The lower court found that the patents were invalid as "obvious" based on "prior art," which means that earlier publications had already disclosed their innovations.

A federal judge's decision last year to invalidate the patents cost Amarin Corp nearly 70% of its stock price. (Reporting by Blake Brittain; Editing by Will Dunham)