Former US vice president Mike Pence revealed on Tuesday he had uncovered documents marked as classified at his home, the latest twist in a mushrooming scandal over politicians' handling of the nation's most sensitive secrets.

Pence, seen as an outside bet for the presidency in 2024, had his lawyer inform the National Archives last week of a "small number" of records that were "inadvertently boxed" and transported to his home in Indiana as he left office in 2021.

He informed the Republican-led House oversight committee about the cache on Tuesday, according to chairman James Comer, who said in a statement Pence had agreed to "fully cooperate with congressional oversight and any questions we have about the matter."

It wasn't immediately clear what information the documents contained or the level of classification they had been allocated.

The discovery comes in the wake of the revelations about classified material discovered in President Joe Biden's private office and residence, and allegations that Biden's predecessor Donald Trump obstructed justice over an FBI probe of a much larger stash of government secrets found at his home.

"Former vice president Pence's transparency stands in stark contrast to Biden White House staff who continue to withhold information from Congress and the American people," Comer added, without mentioning the Trump case.

Pence had asked his lawyer to conduct the search of his home out of an "abundance of caution," CNN reported, citing unnamed sources, and the attorney began going through four boxes stored at Pence's house last week.

"Mike Pence is an innocent man. He never did anything knowingly dishonest in his life. Leave him alone!!!" Trump posted on his Truth Social platform.

The development came as Republicans ramped up their probe of classified documents in the possession of Biden, who was himself vice president under Barack Obama when they were removed from the White House. (AFP)