(CNN) -- The latest twist in the tug of war over Department of Justice documents central to the investigation of Operation Fast and Furious came Friday evening, when a top Justice official refused a congressional request for subpoenaed documents and blamed GOP lawmakers over the leaking of sensitive information.
In a letter to Rep. Darrell Issa, R-California, and Sen. Charles Grassley, R-Iowa, Assistant Attorney General Ronald Weich suggested that sensitive information relating to ongoing investigations is coming from their staffs.
Information from the documents appeared in news reports after it was shared with the lawmakers' staffs, he said.
"While we do not know who provided these letters to reporters, we are deeply disturbed that the sensitive law-enforcement information contained in them has now entered the public realm," Weich said. "This public disclosure is impeding the department's efforts to hold individuals accountable for their illegal acts."
The documents refer specifically to reports of investigation (ROI's) involving an active criminal investigation of a firearms trafficking ring, and to the prosecution of suspect Manuel Celis-Acosta, who awaits trial on felony counts, Weich said.
The Justice official said he was denying Issa's and Grassley's requests for additional documents because of the sensitivity of the ongoing operations.
The ongoing dispute over access to Justice documents stems from an aggressive investigation by Issa's House Committee on Oversight and Government Reform, with Grassley's help, into the origins and impact of the Bureau of Alcohol, Tobacco and Firearms' Operation Fast and Furious. That sting operation allowed agents to monitor illegally purchased long guns in Arizona gun shops. The weapons bought by straw purchasers were then smuggled into Mexico. Hundreds of weapons were then lost, and two of them turned up at the homicide site of a U.S. Border Patrol agent.
Attorney General Eric Holder has acknowledged the flawed tactic, and has vowed that guns will not be allowed "to walk" from gun shops near the border with Mexico.
Friday night, in response to the Justice Department letter refusing the documents, Issa spokeswoman Becca Watkins said, "It is troubling that the attorney general continues to express the outlandish view that his compliance with lawful and binding subpoenas is merely optional."