Rep. Trey Gowdy, chairman of the House Select Committee on Benghazi, struck back Friday at "factual inaccuracies" in a Pentagon letter sent last week that accused his panel of employing overly aggressive tactics to secure witnesses and documents.

Gowdy accused Stephen Hedger, assistant secretary of defense for legislative affairs, of drafting and leaking a partisan letter that "intentionally mischaracterizes" his committee's probe. Hedger's letter had cited several requested interviews that the Pentagon felt were "unnecessary even for a comprehensive investigation."

"Given the importance of the issue and the absolute necessity that the inquiry be full and fair, it is disappointing your staff has found it necessary to challenge the committee's requests for interviews," Gowdy wrote in a letter to Secretary of Defense Ash Carter.

The South Carolina Republican noted that while Hedger had called the pace of the committee's requests over the past two years "unrealistic," Defense Department officials had recently wrapped up a review of the bombing of a civilian medical facility in Afghanistan within two months.

The two-month inquiry into the Kunduz bombing required interviews with 65 witnesses, while the Benghazi committee has only secured 16 witness interviews in two years of work.

As an example of the committee's "unrealistic" pursuits, Hedger cited a committee request to interview an unidentified talk radio show caller who had claimed to be a drone pilot on the night of the Benghazi attack. The Pentagon official claimed his agency unsuccessfully "expended significant resources" to locate the man before congressional investigators demanded the Defense Department provide access to every drone pilot who may have been operating in the area near Benghazi on September 11, 2012.

But Gowdy said his committee had first requested to speak with drone pilots who flew above Benghazi on Sept. 11 and 12 of that year, a move that went unanswered until congressional investigators drafted and approved subpoenas for the pilots. And while the Pentagon offered to set up interviews with those individuals, Gowdy said they had not yet been scheduled.

The request to speak with the radio show caller, Gowdy noted, came after the committee was already looking to speak with drone operators.

The heated exchange between panel Republicans and the Pentagon comes as the committee works to tie up loose ends before a self-imposed deadline hits next month.

Federal agencies have stonewalled many of the committee's requests over the past two years, preventing the panel from concluding its investigation.