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FBI agents searched the Penn Biden Center offices in mid-November, sources confirmed to Fox News, after President Joe Biden's personal attorneys discovered a handful of documents with classified markings there on Nov. 2. The documents were dated to Biden's time as vice president in the Obama administration.

The number of agents involved in the search is unclear, but the president's team was fully aware and gave their consent to the FBI action, according to sources familiar with the investigation into Biden's handling of classified materials.

There was no search warrant involved, and it is unclear whether any additional documents were taken.

The FBI and Department of Justice declined to comment on the search, which was first reported by CBS News. 

HOUSE OVERSIGHT CHAIRMAN COMER BELIEVES HUNTER BIDEN WAS ‘IN PROXIMITY’ TO PRESIDENT'S CLASSIFIED DOCS

An office building housing the Penn Biden Center, a think tank affiliated with the University of Pennsylvania, is seen in Washington, DC, January 10, 2023, following reports that classified documents from the time when US President Joe Biden was serving as Barack Obama's vice president have been found at the center that Biden sometimes used as office space. - Lawyers for Biden discovered the documents last November while clearing out the office space and handed them over to the National Archives, which handles all such materials, Biden's special counsel Richard Sauber said. (Photo by SAUL LOEB / AFP) (Photo by SAUL LOEB/AFP via Getty Images)

An office building housing the Penn Biden Center, a think tank affiliated with the University of Pennsylvania, is seen in Washington, D.C., Jan. 10, 2023. (Saul Loeb / AFP via Getty Images)

President Joe Biden sunglasses

President Joe Biden (AP Photo / Carolyn Kaster / File)

BIDEN DOCS: WHITE HOUSE REQUESTED FBI SEARCH THAT UNCOVERED LATEST BATCH OF CLASSIFIED DOCUMENTS

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. He never taught a full semester's course nor did he conduct any research or have any administrative responsibilities.

The classified documents found in Biden's old offices were one of several batches of such materials found that have created a scandal for the Biden White House. FBI agents also searched and seized classified records from Biden's home in Wilmington, Delaware, on Jan. 20, and the White House had announced the search the day after.  

The FBI search of the Penn Biden Center was not previously disclosed by the White House

Somewhere between 25 and 30 documents with classified markings have now been recovered from Biden's possession and turned over to the National Archives and the Justice Department

BIDEN, TRUMP, PENCE UNDER SCRUTINY FOR CLASSIFIED RECORDS, POTENTIALLY COMPLICATING 2024 WHITE HOUSE BIDS

Robert Hur

Attorney General Merrick Garland recently appointed Robert Hur, above, as a special counsel to investigate the presence of classified records at President Biden’s home in Wilmington, Delaware, and the Penn Biden Center in Washington, D.C. (AP Photo / Steve Ruark / File)

Like his predecessor Donald Trump, Biden is now under special counsel investigation for his retention of classified records.

The White House has repeatedly declined to comment on the contents of the classified records, as well as the levels of the classification, saying instead that the records "have been turned over to proper authorities and will be part of the ongoing investigation."

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Lawmakers have pressed the Biden administration for more transparency but have been met with a "stone wall," according to Democrats on the Senate Intelligence Committee.

Fox News' Ronn Blitzer, Brooke Singman and Bradford Betz contributed to this report.