U.S. President Biden arrives in Mexico
U.S. President Joe Biden arrives at Felipe Angeles International Airport on the outskirts of Mexico City to attend the North American Leaders' Summit, in Santa Lucia, Mexico January 8, 2023. Reuters

Classified documents from Joe Biden's vice-presidential days were discovered in November by the U.S. president's personal attorneys at a Washington think tank, a White House lawyer said on Monday.

Nearly 10 documents were found at Biden's office at the Penn Biden Center for Diplomacy and Global Engagement, CBS News reported earlier, adding that U.S. Attorney General Merrick Garland had asked the U.S. attorney in Chicago to review the classified documents which were handed over to the National Archives.

The classified material was identified by personal attorneys for Biden on Nov. 2, days before the midterm elections, Richard Sauber, special counsel to the president, said in a statement on Monday.

Biden had periodically used that office space from mid-2017 until the start of his 2020 presidential campaign. The White House Counsel's Office notified the National Archives on the day of the discovery of those documents, Sauber said, adding the National Archives took possession of the material on the following morning.

Sauber also said the documents were not the subject of any previous request or inquiry by the National Archives.

The documents were discovered when Biden's personal attorneys "were packing files housed in a locked closet to prepare to vacate office space at the Penn Biden Center in Washington, D.C.," Sauber said. He added the White House was cooperating with the Justice Department and the National Archives.

The Justice Department, the National Archives and the think tank did not immediately respond to a request for comment. Biden was vice president under former President Barack Obama from 2009 to 2017.

Sauber's statement did not mention the number of classified documents or what they contained or their level of classification. CBS News reported that they did not contain nuclear secrets.

The Justice Department is separately probing former President Donald Trump's handling of highly sensitive classified documents that he retained at his Florida resort after leaving the White House in January 2021. FBI agents carried out a court-approved Aug. 8 search of Trump's Mar-a-Lago estate. About 100 documents marked as classified were among thousands of records seized.

"When is the FBI going to raid the many homes of Joe Biden, perhaps even the White House? These documents were definitely not declassified," Trump said in a post on his Truth Social platform late on Monday.