Joe Biden has been questioned as part of the investigation into a series of classified government documents found in an office he used as well as at his family home, the White House announced Monday.

The interrogation, which was described as “voluntary”, took place the day before Sunday and yesterday Monday, according to the US presidency, which assured that “the president and the White House are cooperating” in the investigation conducted by an independent special prosecutor.

In late 2022, a series of classified documents – their exact number and content have not been disclosed – were found in an office used by Mr Biden at a Washington think tank and at his home in Wilmington, Delaware (East).

These documents go back to the period when the Democrat was vice president of the USA (2009-2017) and to his three decades of service in the US Congress, during which he was extensively involved in foreign policy.

Locating these documents has put the White House in an extremely difficult position as the case is comparable, despite its several differences, to the case of the official records that former Republican President Donald Trump took with him to Florida when leaving the presidency.

US law requires presidents and vice presidents to turn over all of their official papers, communications and other materials to the National Archives.

Mr. Biden answered questions put to him by special counsel Robert Herr during the presidency. Mr. Herr was named an independent special prosecutor by US Attorney General Merrick Garland in January.