Sens. Ron Wyden (D-Ore.) and Martin Heinrich (D-N.M.) said in a letter that was partly declassified Thursday that the CIA has been collecting data in bulk in a secret program that could impact Americans' privacy.

In a letter sent to CIA Director William Burns and National Intelligence Director Avril Haines in April, the two Senate Intelligence Committee members called for more information on the program to be declassified.

In addition to declassifying the senators' letter, the CIA also on Thursday declassified a portion of recommendations from a report compiled by a watchdog, the Privacy and Civil Liberties Oversight Board (PCLOB), on the program. Significant portions of both the letter and the recommendations were redacted. The rest of the report remains fully classified.

Wyden and Heinrich allege in the letter that the program has operated outside of laws passed and reformed by Congress but under the authority of Executive Order 12333, a document signed by former President Reagan in 1981 that governs intelligence community activity, according to The Associated Press.

"The CIA has secretly conducted its own bulk program," the lawmakers wrote, with the rest of the line being redacted.

"It has done so entirely outside the statutory framework that Congress and the public believe govern this collection, and without any of the judicial, congressional or even executive branch oversight that comes with FISA collection," they continued, referring to the Foreign Intelligence Surveillance Act. "This basic fact has been kept from the public and from Congress. Until the PCLOB report was delivered last month, the nature and full extent of the CIA's collection was withheld even from the Senate Select Committee on Intelligence."

They called for the CIA to release information on the nature of the agency's "relationship with sources and the legal framework for the collection" as well as the kind of records being collected and how much of Americans' data was being maintained. They also pressed the agency to declassify information on "the rules governing the use, storage, dissemination and queries (including U.S. person queries) of the records."

In a statement, CIA privacy and civil liberties officer Kristi Scott said the agency takes its duty to protect the privacy and personal liberties of U.S. residents seriously.

“CIA recognizes and takes very seriously our obligation to respect the privacy and civil liberties of U.S. persons in the conduct of our vital national security mission,” Scott said, according to the AP. “CIA is committed to transparency consistent with our obligation to protect intelligence sources and methods.”

According to portions of the PCLOB report's recommendations declassified by the CIA, agency analysts using the program that looks for information related to U.S. persons are warned by a pop-up box that doing so requires a foreign intelligence purpose. However, the program does not require analysts to provide a justification for their search, according to the recommendations, which urged the agency to require them to do so.

In a statement following the declassification of the redacted letter and recommendations, Wyden and Heinrich noted that FISA has received scrutiny in the past. 

“But what these documents demonstrate is that many of the same concerns that Americans have about their privacy and civil liberties also apply to how the CIA collects and handles information under executive order and outside the FISA law," they said. "In particular, these documents reveal serious problems associated with warrantless backdoor searches of Americans, the same issue that has generated bipartisan concern in the FISA context.”

They called for the declassification and release of further information on the program beyond the recommendations from the oversight board's report.

“While we appreciate the release of the ‘Recommendations from PCLOB Staff’ which highlights problems associated with the handling of Americans’ information, our letter also stressed that the public deserves to know more about the collection of this information," they said. "The DNI and the CIA Director have started this process. We intend to continue to urge them to achieve the transparency the American people deserve.”