WASHINGTON (Reuters) - New York has opened a probe into whether Mylan Pharmaceuticals <MYL.O> broke antitrust law in writing contracts to provide EpiPens to some schools systems, state Attorney General Eric Schneiderman said in a statement on Tuesday.

A person briefed on the matter said the New York attorney general's office has subpoenaed documents from Mylan over the EpiPen program.

There had been allegations that schools which had used Mylan's EpiPen4Schools program, which gives many schools the devices for free, were contractually barred from buying products from Mylan competitors for a year. Senators Richard Blumenthal and Amy Klobuchar asked the Federal Trade Commission on Tuesday to investigate the allegation.

Mylan did not immediately respond to a request for comment.

(Reporting by Diane Bartz and David Shepardson; Editing by David Gregorio)