The White House on Tuesday criticized "political stunts" by Republicans in the wake of the discovery that President Joe Biden improperly stored classified documents for years among his personal belongings.

The counter-attack comes as the White House faces increasing pressure since the disclosure that a handful of sensitive government documents had been found sitting in Biden's former private office and at his Delaware home.

Congressional Republicans, who took control of the US House of Representatives this month, are "faking outrage," said Ian Sams, spokesman for the White House counsel's office.

House Republicans have recently announced their own probes into the documents' storage, in addition to the investigation run by a Justice Department-appointed special counsel.

"They've decided that it's time for more political stunts," Sams told reporters.

He referred to Republicans' lack of interest in former Republican president Donald Trump's far bigger documents scandal and also raised questions over newly elected Speaker Kevin McCarthy's closed-door deal-making with his party's far right wing.

"When it comes to Congress, we intend to review and respond to oversight inquiries in good faith. But we also expect members of Congress to show the same good faith," Sams said.

"House Republicans lose credibility when they engage in fake outrage about an issue that they're clearly pursuing only for partisan gain."

Sams said the White House is "reviewing" demands made by Republican-led House committees. But "we're going to call it out when we see rampant hypocrisy."

The stray classified documents date from Biden's time as vice president under Barack Obama. He says he was "surprised" to learn of their existence and that the White House is cooperating fully and voluntarily.