A new set of secret federal documents have been discovered by the aides to US Vice President Joe Biden at a second location, adding to the White House's mounting political embarrassment.
The first cache was discovered at Mr. Biden's post-vice-presidential private office in Washington, D.C.
The US Department of Justice is investigating the situation.
Donald Trump, a former president, is under criminal investigation for allegedly handling secret documents improperly.
On Wednesday, it remained unclear when or where Biden's staff discovered the extra batch of documents.
Only this week has the first batch of roughly 10 documents been made public after it was found in November at the Penn Biden Center, a think tank close to the White House.
These documents apparently contain US intelligence notes and briefing materials about the UK, Iran, and Ukraine.
Although it's not obvious why they ended up in the private office he started using after that, they are related to his time serving as vice president under President Barack Obama.
Laws governing how secret materials are kept and stored limit access to them to those with special authorization.
After an administration leaves office, all White House records, including those that are secret, must be given to the US National Archives.
Regarding the recently found batch, the White House has not yet made any remarks. However, CBS, a US partner of the BBC, and other US media outlets have corroborated the discovery.
Karine Jean-Pierre, the press secretary for Biden, declined to respond to inquiries regarding the initial trove of documents during her daily news briefing on Wednesday.
The Department of Justice is looking into this, she said. I won't add anything to what the president said yesterday.
She was questioned about the delay in the news's public release of two months, but she steadfastly refused to explain when Mr. Biden had been informed of it. The revelation was made just a few days before the US midterm elections.
On Tuesday, Mr. Biden stated that he was "surprised" to learn the news and that he was "cooperating" with the law department's investigation.
The debate occurs when a new Republican majority in the US House of Representatives scrutinises the Democratic president.
According to James Comer, the incoming chairman of the House Oversight Committee, "oversight and accountability are coming now that Democrats no longer have one-party rule in Washington."
The committee is looking into the president and his family, and part of that investigation will involve asking the White House to provide records and correspondence pertaining to the classified files.
According to the White House, Mr. Biden's attorneys notified the archives as soon as they found the secret documents at the think tank, and the agency picked them up the following morning.
When Mr. Biden's predecessor's Florida residence was inspected by FBI investigators in August of last year, they found over 10,000 documents that Mr. Trump had not yet given to the National Archives.
Before the FBI arrived at Mar-a-Lago, the justice department had issued a demand for the return of the confidential documents.
Federal authorities seized more than 300 documents with classified markings from the Palm Beach golf club, including 18 with the top secret designation.
Biden submits a timeline
From January 2009 to January 2017, he served as Barack Obama's vice president. From 2018 to 2020, he used a private office in the Penn Biden Center thanks to his connections at the University of Pennsylvania.
First batch of secret documents were discovered at this office on November 2, 2022. CBS News reported on this finding on January 9, 2023.
11 January 2023: NBC News reports on a second discovery made at a different site.
