The controversy comes as Joe Biden faces scrutiny from a new Republican majority in the US House of Representatives. Photo: SAUL LOEB
US President Joe Biden's aides have found a fresh batch of classified government records at a second location, in a growing political embarrassment for the White House.
The first cache was found at a private office in Washington DC that Biden used after his vice-presidency.
The matter is under review by the US Department of Justice.
Donald Trump faces a criminal investigation for allegedly mishandling classified files.
It was unclear on Wednesday when or where the additional tranche of files was found by Biden aides.
The original batch of about 10 documents was discovered in November at the Penn Biden Centre, a think tank near the White House, but only came to light this week.
Those papers reportedly include US intelligence memos and briefing materials related to Ukraine, Iran and the United Kingdom.
At Wednesday's daily press briefing, White House press secretary Karine Jean-Pierre declined to answer questions about the first cache of files.
"This is under review by the Department of Justice" she said. "I'm not going to go beyond what the president shared yesterday."
Biden said on Tuesday he was "surprised" by the discovery of the files and was "co-operating" with the justice department's review.
The controversy comes as the Democratic president faces scrutiny from a new Republican majority in the US House of Representatives.
"Now that Democrats no longer have one-party rule in Washington, oversight and accountability are coming," James Comer, the new chairman of the House Oversight Committee, said on Wednesday.
The committee is launching inquiries into the president and his family, including a request for the White House to turn over documents and communications related to the classified files.
The law requires that all White House records, including classified ones, be turned over to the US National Archives, after an administration's time in office.
Last August, FBI agents searched the Florida home of Biden's predecessor and seized more than 10,000 files that Trump had failed to turn over to the Archives.