US President Joe Biden’s aides have discovered a new set of sensitive government data at a second location, adding to the White House’s mounting political humiliation.
The first cache was discovered at a private office in Washington DC that Mr Biden used after leaving the vice president.
The US Department of Justice is investigating the situation.
Former President Donald Trump is being investigated for potentially mishandling secret documents.
On Wednesday, it was unclear when or where the fresh tranche of data was discovered by Biden aides.
The first set of perhaps ten documents was discovered in November at the Penn Biden Center, a think tank near the White House, but was just recently made public.
These files are said to contain US intelligence memoranda and briefing materials on Ukraine, Iran, and the United Kingdom.
The White House has yet to respond to the recently revealed batch. The discovery, however, has been corroborated by the BBC’s US partner CBS and other US media outlets.
Karine Jean-Pierre, Biden’s press secretary, declined to address questions regarding the first batch of data during her daily news conference on Wednesday.
“The Department of Justice is looking into it,” she stated. “I’m not going to go any farther than what the president said yesterday.”
Mr. Biden said on Tuesday that the discovery of the data had “surprised” him and that he was “cooperating” with the Justice Department’s investigation.
The debate arises as the Democratic president faces more scrutiny from a new Republican majority in the United States House of Representatives.
“Oversight and accountability are coming now that Democrats no longer have one-party dominance in Washington,” James Comer, the incoming chairman of the House Oversight Committee, said on Wednesday.
The committee is conducting investigations into the president and his family, including a request for the White House to turn over secret papers and communications.
The law mandates that all White House documents, including secret information, be given over to the US National Archives at the end of an administration’s tenure.
According to the White House, Mr. Biden’s attorneys notified the archives as soon as they discovered the secret files at the think tank, and the agency removed them the following morning.
Last August, FBI officials raided Mr Biden’s predecessor’s Florida residence and collected over 10,000 files that Mr Trump had not given over to the National Archives.
Before the FBI arrived to Mar-a-Lago, the Justice Department had issued a subpoena demanding the return of the classified materials.
Federal authorities collected more than 300 documents with classified markings, including 18 designated top secret, from a Palm Beach golf club.