US President Joe Biden “wilfully” retained and disclosed highly classified materials when he was a private citizen, including documents about military and foreign policy in Afghanistan and other sensitive national security matters, according to a Justice Department report.

The report from special counsel Robert Hur, which was released on Thursday, represents a harshly critical assessment of Mr Biden’s handling of sensitive government materials, but also details the reasons why he should not be charged with the crime.

The findings will likely blunt his ability to forcefully condemn Donald Trump, Mr Biden’s likely opponent in November’s presidential election, over a criminal indictment charging the former president with illegally hoarding classified records at his Mar-a-Lago estate in Florida.

“Our investigation uncovered evidence that President Biden wilfully retained and disclosed classified materials after his vice presidency when he was a private citizen,” Mr Hur wrote.

It came after a year-long investigation into the improper retention of classified documents by Mr Biden, from his time as a senator and as vice president, that were found at his Delaware home, as well as at a private office that he used in between his service in the Obama administration and becoming president.

The investigation into Mr Biden is separate from special counsel Jack Smith’s inquiry into the handling of classified documents by Trump after the Republican left the White House.

Mr Smith’s team has charged Trump with illegally retaining top secret records at his Mar-a-Lago home and then obstructing government efforts to get them back. Trump has said he did nothing wrong.

After Mr Biden’s lawyers uncovered classified documents at his former office, his representatives promptly contacted the National Archives to arrange their return to the government.

The National Archives notified the FBI, which opened an investigation. Mr Biden made his homes available to agents to conduct thorough searches, and that is how the most sensitive documents came to the attention of the Justice Department.

Mr Biden could not have been prosecuted as a sitting president, but Mr Hur’s report states that he would not recommend charges against Mr Biden regardless.

“We would reach the same conclusion even if Department of Justice policy did not foreclose criminal charges against a sitting president,” the report said.

According to the report, evidence suggests that many of the classified documents recovered by investigators at the Penn Biden Centre, in parts of Mr Biden’s Delaware home, and in his Senate papers at the University of Delaware were retained by “mistake”.

Mr Biden said in a statement the was “pleased” the special counsel had “reached the conclusion I believed all along they would reach — that there would be no charges brought in this case and the matter is now closed”.

He made a point of saying that he sat for five hours of in-person interviews over two days on October 8 and 9, “even though Israel had just been attacked on October 7th and I was in the middle of handling an international crisis”.

“I just believed that’s what I owed the American people so they could know no charges would be brought and the matter closed,” Mr Biden added.

Part of the report centres on Mr Biden’s handling of classified documents about Afghanistan — specifically, the Obama administration’s decision to send additional troops there — that he retained after he left office as vice president in his Delaware home.

Mr Biden preserved materials documenting his opposition to the troop surge, including a 2009 classified handwritten memo to then-president Barack Obama.

“These materials were proof of the stand Mr Biden took in what he regarded as among the most important decisions of his vice presidency,” the report said.

The documents have classification markings up to the Top Secret/Sensitive Compartmented Information level and were found in a box in Mr Biden’s Delaware garage “that contained other materials of great significance to him and that he appears to have personally used and accessed”.

Photographs included in the report showed some of the classified Afghanistan documents stored in a worn cardboard box stored in his garage, apparently in a loose collection with other household items, including a ladder and a wicker basket.

Classified documents from the Obama administration were also found in Mr Biden’s basement den, according to the report. Classified documents from his time in the Senate in the 1970s and 1980s were also found in his garage.

Despite signs that Mr Biden knowingly retained and disclosed classified materials, Mr Hur’s report said criminal charges were not merited for multiple reasons.

These include the fact that as vice president, and during his subsequent presidency when the Afghanistan records were found, “he had the authority to keep classified documents at his home”.

Attorney general Merrick Garland in January 2023 named Mr Hur, a former lawyer for Maryland, to handle the politically sensitive Justice Department inquiry in an attempt to avoid conflicts of interest.

It is one of three recent Justice Department investigations into the handling of classified documents by politically prominent figures.