WASHINGTON, Sept. 27 — The State Department said Thursday that Blackwater USA security personnel had been involved in 56 shootings while guarding American diplomats in Iraq so far this year. It was the first time the Bush administration had made such data public.

Blackwater, a large, privately held security contractor based in North Carolina, provided security to diplomats on 1,873 convoy runs in Iraq so far this year, and its personnel fired weapons 56 times, according to a written statement by Deputy Secretary of State John D. Negroponte.

The State Department did not release comparable 2007 numbers for other security companies, but the new Blackwater numbers show a far higher rate of shootings per convoy mission than were experienced in 2006 by one of the company’s primary competitors, DynCorp International. DynCorp reported 10 cases in about 1,500 convoy runs last year.

The New York Times reported Thursday that Blackwater’s rate of shootings was at least twice as high as the rates for other companies providing similar services to the State Department in Iraq.