WASHINGTON - A CIA plan to erase tens of thousands of its internal emails - including those sent by virtually all covert and counterterrorism officers after they leave the agency - is drawing fire from Senate Intelligence Committee members concerned that it would wipe out key records of some of the agency's most controversial operations.

The agency proposal, which has been tentatively approved by the National Archives, "could allow for the destruction of crucial documentary evidence regarding the CIA's activities," Senate Intelligence Committee Chair Dianne Feinstein and ranking minority member Senator Saxby Chambliss, a Republican, wrote in a letter to Margaret Hawkins, the director of records and management services at the archives.

But agency officials quickly shot back, calling the committee's concerns grossly overblown and ill informed. They insist their proposal is completely in keeping with - and in some cases goes beyond - the email retention policies of other government agencies. "What we've proposed is a totally normal process," one agency official said, according to media reports.

The source of the controversy may be that the CIA, given its secret mission and rich history of clandestine operations, is not a normal agency.

And its proposal to destroy internal emails comes amid mounting tensions between the CIA and its Senate oversight panel, stoked by continued bickering over an upcoming committee report - relying heavily on years-old internal CIA emails - that is sharply critical of the agency's use of waterboarding and other aggressive interrogation techniques against al-Qaeda suspects in the aftermath of the 9/11 terror attacks.

In this case, however, Chambliss - a conservative Republican who has sided with the CIA on the interrogation issue - joined with Feinstein in questioning the agency's proposed new email policy, which would allow for the destruction of email messages sent by all but a relatively small number of senior agency officials.

"In our experience, email messages are essential to finding CIA records that may not exist in other so-called permanent records," the two senators wrote in their letter, a copy of which was also sent this week to CIA Director John Brennan and Director of National Intelligence James Clapper.

The agency proposal was initiated as a response to a government-wide problem: how to preserve emails that constitute legitimate "federal records," loosely defined as dealing with the "public business" or the "functions, policies, decisions, procedures, and operations" of the government - all of which are required to be permanently retained under the law known as the Federal Records Act.

The CIA proposal, submitted to the National Archives last January but only made public in recent weeks, would replace what officials acknowledge is an imperfect and inconsistently followed current policy that directs agency officials, on their own initiative, to "print and preserve" emails that might constitute federal records.