Republicans accuse Biden of hypocrisy over classified files.

Republicans have accused US President Joe Biden of hypocrisy after more confidential documents were discovered at his Delaware residence.

"Don't cast stones if you live in a glass house," Nebraska congressman Don Bacon said on ABC's This Week.

At least 20 documents relating to Mr. Biden's term as vice president have been discovered at his private residence and a Washington office he used.

He chastised Donald Trump when his residence was raided for confidential documents.

"How could somebody be that careless?" he wondered at the time.

Mr. Trump is being investigated by a special counsel in connection with the discovery of hundreds of secret materials at his Mar-a-Lago club last year.

Because archivists said his team was not handing over all of the missing records, the FBI conducted a raid.

• Four questions concerning the Biden documents remain unresolved.
• Who is the special counsel in the Biden investigation?
• How the secret files cases of Biden and Trump compare

Mr. Biden is also being probed by Robert Hur, a special counsel assigned by the US Department of Justice to conduct an independent investigation of the president's handling of sensitive documents.

The contents of the documents discovered in Mr. Biden's possession are unknown, although CBS News reports that some of them were marked "Top Secret," the highest level of classification.

At the end of a presidency, all White House files are required by law to be turned over to the National Archives.

On Sunday, some Republicans turned to the radio to accuse Mr. Biden of hypocrisy.

The incoming chair of the House oversight committee, Kentucky's James Comer, told CNN's State of the Union, "While he was doing this [accusing Trump], he knew quite well that he himself had custody of secret documents, so the hypocrisy here is huge."

Some Democrats have expressed alarm over the papers, including House Representative Adam Schiff, who told This Week that he wants to know "whether there was any risk of disclosure and what the harm might be" to national security as a result of the misplaced records.

The White House has not stated how long Mr. Biden was aware of the records in his possession, but they insist his lawyers turned them over as soon as they discovered them.

It's unclear what punishments Mr. Biden could face, but experts say criminal charges are improbable since prosecutors would have to prove the president and his advisers deliberately removed and stored the materials.

Mr. Biden himself stated that learning they were discovered there surprised him and that he takes the handling of sensitive material extremely seriously.

The first batch was discovered in his previous office on November 2, just days before the midterm elections, but it wasn't made public until last week.

Marc Short, a former key aide to Mr. Trump's Vice President Mike Pence, indicated on Sunday that the information was purposefully delayed to avoid the last days of the election campaign.

Several Republicans have requested that visitor logs to Mr. Biden's homes be made public in order to determine who may have had access to the material.