Former US Vice President Mike Pence said on Friday that he did not know there were classified documents at his home in the state of Indiana and that he takes "full responsibility" for the security breach.

Pence, speaking at Miami International University, said an audit of his personal archives is currently underway after classified documents were found at President Joe Biden's home in Delaware.

We discovered that among my personal documents, a small number were marked as classified or sensitive, Pence said.

He added that he was not aware that they were in his home.

Let me be clear, these classified documents were not supposed to be in my private residence. Mistakes were made and I take full responsibility, Pence said.

Confidential documents were also found in former President Donald Trump's Florida home.

Pence's lawyer, Greg Jacobs, sent a letter to the US National Archives on January 18 notifying him of the documents, and in another letter on January 22, he wrote that the Federal Bureau of Investigation (FBI) entered the former vice president's home to seize them.

Our national security depends on the proper management of classified and sensitive materials, and I know that when mistakes are made, it is important that they are addressed quickly and transparently, Pence said.

The current president of the United States, Biden and Trump, are facing separate investigations by the Department of Justice for the improper management of classified materials.

US presidents and vice presidents are required to return government documents to the National Archives after their terms end. It is unlawful to knowingly or intentionally remove or retain confidential material.