WASHINGTON — Aides to President Joe Biden have discovered at least one additional batch of classified documents in a location separate from the Washington, D.C., office he used after leaving the Obama administration, according to a person familiar with the matter.
Since November, following the discovery of documents with classified markings in his former office, Biden aides have been searching for any additional classified materials that might be in other locations he used, the source, who spoke on the condition of anonymity to provide details about the ongoing inquiry, said.
 The White House did not return a request for comment.
The initial discovery of classified documents in an office used by Biden after his vice presidency was first reported on Monday by CBS News.
The classification level, number and precise location of the additional documents was not immediately clear. It also was not immediately clear when the additional documents were discovered and if the search for any other classified materials Biden may have from the Obama administration is complete.
Biden aides have been sifting through documents stored at locations beyond his former Washington, D.C., office to determine if there are any other classified documents that need to be turned over to the National Archives and reviewed by the Justice Department, the person familiar with the matter said.
The search was described as exhaustive, with the goal of getting a full accounting of all classified documents that may have inadvertently been packed in boxes when Biden cleared out of the vice president’s office space in January 2017.
The White House on Monday issued a statement confirming that a “small number of documents” with classified markings that appeared to be from the Obama administration had been found at a Washington, D.C. think tank tied to Biden back on Nov. 2.
The documents were discovered in a locked closet by Biden’s attorneys while they prepared to vacate office space at the Penn Biden Center for Diplomacy and Global Engagement, Richard Sauber, special counsel to the president, said in a statement Monday.
The University of Pennsylvania had leased a suite of offices for the center in February 2018, including one for then-private citizen Biden’s personal use when he was in Washington.
Biden told reporters Tuesday that he was “surprised” by the discovery, and that he didn’t know what was in the documents.
The chair and vice-chair of the Senate intelligence committee have written to DNI Avril Haines asking for access to the classified documents, a damage assessment by the intelligence community and a briefing on both the Biden and Trump documents, three congressional staffers said. This request is similar to how the committee requested information after the Mar-a-Lago raid, the staffers said.
Sauber said Biden’s lawyers immediately reached out to National Archives about the find, and the agency took control of the documents the next day.
Two sources familiar with the matter said less than a dozen documents with classified markings were found at the office.
The Archives referred the matter to the Justice Department.
U.S. Attorney General Merrick Garland has asked John R. Lausch, U.S. attorney for the Northern District of Illinois and a holdover Trump appointee, to review how the classified material ended up in the closet, a source familiar with the matter told NBC News on Monday.
“We’re cooperating fully,” Biden said Tuesday.
Former President Donald Trump’s possession of over 100 documents with classified markings despite have been subpoenaed for their return is the subject of a federal criminal investigation by the Justice Department.
Trump’s repeatedly mocked Biden over the find on his Truth Social account, while suggesting he’d been unfairly targeted by federal investigators, despite the very different fact sets between his and Biden’s cases. “A giant Scam,” he wrote.