Former US President Joe Biden has sued the federal government to block the release of interviews with his memoir's ghostwriter, which he has described as "private information" but could contain embarrassing details about his memory.

Special Counsel Robert Hur obtained the recordings and transcripts while investigating Biden's handling of classified documents.

Hur found Biden improperly retained records, but he did not recommend charges. His report, released in 2024, also raised questions about Biden's fitness for office.

The justice department has accused the prior administration of trying to "hide audio recordings that clearly demonstrate a significant decline" in Biden's mental state.

House Republicans and a conservative think tank requested the memoir interview records in 2024, and the justice department has indicated they will release them by 15 June.

As part of drafting his 2017 memoir Promise Me, Dad, Biden spoke with co-writer Mark Zwonitzer about events surrounding the death of his elder son Beau in 2015.

Hur said in his report, citing recordings with Zwonitzer, that during the interviews Biden referred to notes he had taken while serving as vice-president, some of which appeared to contain classified information.

The special counsel observed in the report that "Mr Biden's memory also appeared to have significant limitations" and he described the interviews with Zwonitzer as "painfully slow, with Mr Biden struggling to remember events and straining at times to read and relay his own notebook entries".

Hur's report caused a firestorm in Washington and put a spotlight on Biden's age and health. Biden eventually ended his run for re-election after a disastrous debate performance that raised concerns among fellow Democrats.

Republicans, meanwhile, began looking into impeaching Biden, and lawmakers on three congressional committees sought the memoir interview records as evidence . The Heritage Foundation, a conservative think tank, also fought in court to obtain them.

The justice department previously opposed the release of the memoir interviews due to privacy concerns. Under President Donald Trump, however, it has changed course.

"Joe Biden's Justice Department tried to hide audio recordings that clearly demonstrate a significant decline in his cognitive abilities as far back as 2016," Justice Department Spokesperson Natalie Baldassarre said in a statement. "We will fight to ensure the American people can hear these recordings and draw their own conclusions about the former President's mental acuity before he sought the presidency."

In his lawsuit, Biden's attorneys described the conversations as private and sensitive. They argued the materials were protected by the Privacy Act, and that the justice department was violating the Administrative Procedure Act, which sets out the legal guidelines for how the government operates.

They also accused the justice department of using a false justification "to disclose records reflecting President Biden's private conversations for the sake of exposure, among other improper purposes."