EXCLUSIVE: Nine boxes of documents were taken from President Biden's attorney Patrick Moore's Boston office, but have yet to be reviewed, the National Archives disclosed in a response letter to Sens. Ron Johnson, R-Wis., and Chuck Grassley, R-Iowa, this week first obtained by Fox News Digital.

The Archives had not previously publicly disclosed the number of boxes taken from Boston. It had been reported that Moore had shipped boxes of documents from the Penn Biden Center to his Boston office before discovering the initial trove of classified documents at the Washington, D.C.-based think tank.

In response to questions by Johnson and Grassley in a Feb. 24 letter asking how and when the archives learned that records were transported to Boston, Acting Archivist of the United States Debra Steidel Wall responded the agency learned about it on Nov. 3, 2022.

WHAT WE KNOW SO FAR: TIMELINE OF BIDEN'S CLASSIFIED DOCUMENTS DEBACLE

Biden conference speech

Nine boxes of documents were taken from President Biden's attorney Patrick Moore's Boston office. (Drew Angerer/Getty Images)

"When NARA [National Archives and Records Administration] contacted President Biden’s personal counsel on November 3, 2022, to arrange to pick up boxes from the Penn Biden Center in Washington, D.C., they informed NARA that Mr. Moore had moved other boxes from the Penn Biden Center to Mr. Moore’s law firm in Boston," the letter states.

In addition, the archives notified the Department of Justice's Office of Inspector General on Nov. 4 that the documents had been moved. The documents were then picked up on Nov. 9 and were secured in the John F. Kennedy Presidential Library in Boston.

"NARA staff retrieved nine boxes from Mr. Moore’s Boston office," Wall continued, which had not been previously known. 

Wisconsin Senator Ron Johnson

Sen. Ron Johnson, R-Wis. (AP Photo/Morry Gash)

Despite having possession of the documents since November, the Archives has not yet reviewed the boxes' content to determine whether additional classified materials are inside.

"NARA has not reviewed the contents of the boxes found at Mr. Moore’s Boston office," Wall states in the letter dated Tuesday.

AG GARLAND APPOINTS SPECIAL COUNSEL TO INVESTIGATE BIDEN CLASSIFIED DOCUMENTS

Fox News previously reported that FBI agents searched the Penn Biden Center offices in mid-November after President Biden's personal attorneys discovered a handful of documents with classified markings there on Nov. 2.

Biden Delaware

The Penn Biden Center for Diplomacy and Global Engagement is a think tank in Washington, D.C., affiliated with the University of Pennsylvania. (MANDEL NGAN/AFP via Getty Images)

The Penn Biden Center for Diplomacy and Global Engagement is a think tank in Washington, D.C., affiliated with the University of Pennsylvania. Biden used the sixth-floor office space there between 2017 and 2019, during which time he was an honorary professor and received about $900,000 for giving roughly a dozen lectures and talks.

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Additional classified documents were found by Biden's attorneys in his Wilmington, Delaware, house next to his garage. Six items with classification markings were seized after the DOJ searched the home.

Attorney General Merrick Garland appointed Robert K. Hur as special counsel to investigate the handling of Biden's classified documents.