US President Donald Trump says he is terminating all documents, including pardons, signed by his predecessor Joe Biden using an autopen signature.

The autopen is a device used to replicate a person’s signature with precision, typically for high-volume or ceremonial documents.

It has been employed by presidents of both major parties to sign letters and proclamations.

“Anyone receiving ‘Pardons,’ ‘Commutations,’ or any other Legal Document so signed, please be advised that said Document has been fully and completely terminated, and is of no Legal effect,” Mr Trump wrote on Truth Social on Tuesday.

Mr Trump and his supporters have made a variety of unfounded claims that Mr Biden’s use of the device while president invalidated his actions or suggested that he was not fully aware of these actions.

A framed picture of an autopen.

An image of an autopen is displayed in the White House Presidential Walk of Fame in place of Joe Biden’s portrait. (Reuters: Kevin Lamarque )

It is not known whether Mr Biden used an autopen on pardons.

Before leaving office in January, Mr Biden issued several pardons, including for family members he wanted to protect from politically motivated investigations.

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He also commuted sentences, including for non-violent drug offenders.

Mr Trump, known for his provocative style and dislike for his political opponents, has repeatedly targeted Mr Biden’s use of the autopen to sign official documents during his presidency.

Mr Trump has questioned Mr Biden’s mental fitness and suggested that aides, not Mr Biden himself, made key decisions.

Mr Biden and his former aides have denied these claims, emphasising the president’s active role in governing.

Reuters