WASHINGTON (Reuters) - The chairman of the U.S. Senate Judiciary Committee probing Mylan NV's EpiPen price hike on Friday said its response to his query was "incomplete," and called on the drugmaker to give more details over how much government health insurance programs pay for the allergy treatment.

"It's an incomplete response and wouldn't satisfy my constituents who are upset about the EpiPen price increases. It doesn't provide the full picture that I requested, and it doesn't answer all of my questions," U.S. Senator Chuck Grassley said in a statement. He added that it is still unclear how many patients will benefit from Mylan's expanded assistance programme.

(Reporting by Susan Heavey, editing by G Crosse)