UPDATE 1-Bayer sues Teva in U.S. for patent infringement

* Teva seeks to sell generic form of Levitra in U.S.

* Bayer's U.S. patent for Levitra expires in 2018

* Drug sold by Schering-Plough and GlaxoSmithKline in U.S.

FRANKFURT, July 1 (Reuters) - German drugmaker Bayer BAYG.DE said it is suing Israeli generic competitor Teva (TEVA.TA) in a U.S. court for infringing its patent that prevents a Levitra copycat impotence treatment to be sold there.

"The lawsuit concerns Teva's application to the FDA for approval to market a generic form of Levitra, Bayer Schering Pharma's therapy for the treatment of erectile dysfunction, prior to patent expiration," Bayer said in a brief statement on Thursday.

"The patent at issue in the suit is Bayer Schering Pharma's U.S. Patent No. 6,362,178, expiring in 2018."

Bayer said it filed the patent infringement lawsuit in the U.S. Federal Court in the District of Delaware against Teva Pharmaceuticals USA Inc and Teva Pharmaceutical Industries Ltd.

Levitra is marketed by Schering-Plough SGP.N and GlaxoSmithKline (GSK.L) in the United States. (Reporting by Christiaan Hetzner; Editing by Steve Orlofsky)