July 19 (Reuters) - U.S. regulators have declined to approve Novartis' so-called biosimilar copy of Amgen's Neulasta drug that fights infections in cancer patients, the Swiss drugmaker said on Tuesday.

Vasant Narasimhan, head of development at Novartis Pharmaceuticals, said the Food and Drug Administration (FDA) had issued a complete response letter for the product at the end of June, without giving further details.

The FDA typically issues such letters when more information is needed to allow approval. Novartis' copy of Neulasta, whose generic name is pegfilgrastim, had been accepted for review by the U.S. regulator in November.

The drug filing marked the company's third biosimilar filing in the United States.

(Reporting by Ben Hirschler; editing by Susan Thomas)