WASHINGTON — The FBI searched the offices of the Penn Biden Center for Diplomacy and Global Engagement in mid-November after classified documents were discovered there, two senior law enforcement officials confirmed to NBC News on Tuesday.

The officials said President Joe Biden’s lawyers cooperated with the search and no search warrants were used. NBC News does not know the exact date of the search or whether classified documents or anything else of importance were found. The FBI search was first reported by CBS News.

Biden’s lawyers had originally found some classified documents at the Penn Biden Center in an office used by the president on Nov. 2. Biden’s lawyers said they immediately notified the Department of Justice and the National Archives about what was discovered.

Neither the White House nor Biden’s personal lawyers had previously divulged information about the FBI’s search in November. The FBI also searched Biden’s residence in Wilmington, Delaware, earlier this month after the president’s lawyers offered to provide access to his home.

As a result of that search, six additional items, including documents with classified markings, were found in Biden’s Delaware home, said Bob Bauer, the president’s personal attorney.

The documents at the Wilmington home appeared to be related to Biden’s time as vice president, Bauer said, as well as to his tenure in the Senate, and they were found after Biden’s counsel offered full access to the premises.

A pair of Republican-led congressional committees in the House are investigating Biden’s handling of classified documents and Attorney General Merrick Garland appointed a special counsel to lead the federal government’s probe.

In early January, a White House lawyer revealed the discovery of “a small number of documents” with classified markings at the Penn Biden Center in November, just a few days before the midterm elections. They had been found in a locked closet by Biden’s attorneys as they prepared to vacate office space at the Penn Biden Center.

Meanwhile, former President Donald Trump has been under investigation over his possession of classified documents at Mar-a-Lago. Last summer, FBI agents executed a search warrant at the Florida resort. The search uncovered more than 100 documents with classification markings, including some marked top secret. In December, it was reported that two more documents with classified markings were found in a Florida storage facility not far from Trump’s Palm Beach resort and were turned over to the FBI.

After the reports that classified documents had been in Biden’s possession, former Vice President Mike Pence asked outside counsel earlier this month to look for records bearing classified markings at his home in Indiana. Pence’s lawyers said a “small number” were found at the residence.