A U.S. district court ruled against the validity of Bayer Schering Pharma's patent for its contraceptive drug Yasmin, the German drug company said late on Monday.

This was the result of a patent challenge by generic manufacturer Barr Laboratories, Bayer said in a statement.

"Bayer disagrees with the court's decision and will consider its legal options in this regard," the company added.

Bayer Schering's contraceptive drug Yasmin has annual sales of more than one billion euros. Sales of Yasmin in the United States came in at 321 million euros ($486.9 million) last year, it said.