A federal judge on Tuesday dismissed a lawsuit seeking to halt sales of the only "morning-after" contraceptive pill available in the United States without a prescription.

The suit was filed against U.S. health regulators over their decision to allow non-prescription sales of Barr Pharmaceuticals Inc's Plan B pill.

The U.S. Food and Drug Administration and Barr were sued by the Association of American Physicians and Surgeons and other groups seeking to overturn the FDA decision.

The pill can reduce the risk of pregnancy when taken within three days of intercourse.

The U.S. District Court for the District of Columbia granted the FDA's and Barr's motion to dismiss the suit, saying the plaintiffs had failed "to identify a single individual who has been harmed by Plan B's OTC (over-the-counter) availability," according to the ruling.

Backers of reproductive rights applauded the decision.

"They still don't have any evidence in terms of why they think it is harmful," said Janet Crepps, deputy director for domestic programs at the Center for Reproductive Rights. "This is the right decision for women."

Plan B was approved in 1999. The FDA broadened the approval in 2006 to allow sale to adults without a prescription.

The pills must be kept behind pharmacy counters and can be sold to girls under the age of 18 years only with a doctor's order.