The US Department of Justice (DoJ) discovered six more classified documents during a 13-hour search of President Joe Biden's home in Delaware, according to Mr Biden's lawyer.
Some of the documents seized on Friday at his Wilmington home were from his time as a senator, while others were from his time as Vice President under Barack Obama.
According to lawyer Bob Bauer, "personally handwritten notes" and "surrounding materials" were also taken.
The president granted access "to his home to allow DoJ to conduct a search of the entire premises for potential vice-presidential records and potential classified material," Mr Bauer said in a statement on Saturday.
Mr Biden and his wife were not present.
Earlier this month, Mr Biden's lawyers announced that a first batch of classified documents had been discovered on November 2 at the Penn Biden Center, a Washington DC think tank founded by the president.
A second batch of records was found on 20 December in the garage at his Wilmington home, while another document was found in a storage space at the house on 12 January, his lawyers said.
Under the Presidential Records Act, White House records are supposed to go to the National Archives once an administration ends, where they can be stored securely.
The two-month gap between the first Biden discovery, just days before the midterm elections, and the news being made public in January raises awkward transparency questions for the president.
The discovery comes as former US President Donald Trump is also being investigated for allegedly mishandling hundreds of classified documents at his Florida Mar-a-Lago estate and failing to comply with a subpoena.
Mr. Trump and his attorneys refused to turn over the documents until the FBI raided his Florida vacation home last August. He claims that the FBI is treating President Biden more favorably.
