WATCH: Joe Biden has 'poor memory', special counsel report concludes

A special counsel report by Robert Hur revealed its findings on the probe into United States President Joe Biden’s handling of top secret files during his vice presidency on Thursday, BBC reported.

Investigators conducted 173 interviews with 147 witnesses, including Biden himself, whom Hur said seemed to be a "sympathetic, well-meaning, elderly man with a poor memory".

During the investigation, the Federal Bureau of Investigation (FBI) agents found restricted files from "the garage, offices, and basement den in Biden's Wilmington, Delaware, home" related to military and foreign policy in Afghanistan.

While the investigation found that Biden purposely "retained and disclosed classified materials" after leaving office, Hur stated that the evidence wasn't enough to charge any offences against him.

Biden has criticised the investigation, and denied claims of his memory being "poor" and "faulty."

Biden blasted in front of the media, telling a reporter, "I'm well-meaning; I'm an elderly man, and I know what the hell I'm doing."

"I've been the president; I put this country back on its feet. I don't need his recommendation."

As additional questions about his old age and memory were asked, Biden became even more rattled, telling off the reporter. "My memory is so bad, I let you speak."

But just minutes after defending his memory and cognition, Biden misspoke and called President of Egypt Abdel Fattah al-Sisi the "president of Mexico", CNN reported.