The FBI and the CIA conducted an untold amount of warrantless “backdoor searches” on thousands of private American citizens, according to an internal document (PDF) released Monday by the Office of the Director of National Intelligence.

The document was released to leaders of the Senate Intelligence Committee following a request by Sen. Ron Wyden (D-Ore.) who expressed specific concern over the agency’s use of the government’s mass surveillance apparatus, which he has called unnecessary and overly intrusive.

The ODNI document revealed that the CIA carried out nearly 1,900 warrantless searches in 2013. The FBI, however, confirmed it does not track the number of queries it conducts and could only say that it was a “substantial” amount.

“When the FBI says it conducts a substantial amount of searches and it has no idea of what that number is, it shows how flawed this system is and the consequences of inadequate oversight,” Wyden said in response to agency’s statement. “The findings […] raise questions about whether the FBI is exercising any internal controls over the use of backdoor searches including who and how many government employees can access the personal data of individual Americans.”

Senate Intelligence Committee aides told the Washington Post in November that there have only been a “small number” of queries each year. As independent journalist Marcy Wheeler wrote on the issue, “[It’s] a damn good thing Ron Wyden asked for and insisted on getting an answer to his question of how common these backdoor searches are… Because the key people who are supposed to oversee them are either ignorant or lying about them.”

The CIA and FBI have joined the NSA in using Section 702 of the Foreign Intelligence Surveillance Act (FISA) to gather information about individual U.S. citizens by spying on their emails, telephone calls, and other wireless communications.