The US Supreme Court has declined to act on patent settlements by drug companies following allegations that they may violate federal antitrust laws.

The allegations relate to private settlements made by drug companies, in which rivals could be paid to delay production of generic drugs.

The justices refused to review a US appeals court ruling that dismissed a legal challenge over Bayer paying Teva Pharmaceutical unit Barr Laboratories in order to prevent the company from marketing a generic version of antibiotic Cipro.