US federal prosecutors have filed three new criminal charges against former President Donald Trump in connection with his alleged mishandling of classified documents after leaving office.

They come on top of charges that include violating the Espionage Act that were filed against Trump last month. That initial indictment accused him of illegally retaining sensitive documents containing information on nuclear weapons and military capabilities at his residence in Florida.

On Thursday, the Justice Department unveiled the three additional counts, including a charge of obstruction of justice.

The revised indictment says Trump and his aides told an employee at his Mar-a-Lago residence to delete a server holding security camera footage. The move came after federal investigators issued a subpoena for the footage.

Trump now faces 40 criminal counts in connection with the case.

Trump's campaign released a statement saying, "This is nothing more than a continued desperate and flailing attempt by the Biden Crime Family and their Department of Justice to harass President Trump and those around him."

The former president remains under investigation by a special counsel over the January 2021 assault on the Capitol by Trump supporters seeking to overturn his election loss.

Trump, who is the first former president to face federal criminal charges, is seeking to reclaim the White House in 2024.