US President Joe Biden takes classified documents and information “very seriously”, the White House said, hours after it revealed that more classified documents were found at his residences and private offices.

The attorney-general has appointed a special counsel, Robert Hur, to investigate the discovery of classified documents at the Penn Biden Center in Washington and the Bidens’ personal residence in Wilmington, Delaware.

“It is important for the American people to know this, is that the President has said, he takes classified documents and information very seriously,” White House press secretary Karine Jean-Pierre said.

“This is something, as you all know, that he will not shy away from saying and has continued to say this week. And again, he was surprised that these records have been found.

“He does not know what’s in them and his team, once they identified that these documents were there, they immediately reached out to the archives of the department of justice and did the, rightfully so, the right thing by turning that over,” she said.

“And they have been cooperating very closely with the department of justice. Attorney-General Garland, say today that they heard from his team really shortly after the discovery. And so I just want to make sure that this is understood, that he takes this very seriously,” Jean-Pierre said.