A French "nationalist" has been arrested and charged over an alleged plan to kill President Emmanuel Macron on Bastille Day when he is due to oversee a military parade with US counterpart Donald Trump.

The unemployed 23-year old from the Paris suburb of Argenteui was seized after expressing an interest in acquiring a real machine gun in a video game chatroom, according to RMC radio. He threatened police with a kitchen knife during the arrest. Officers found three knives in his car, the radio reported.

His computer contained a search history of potential targets.

The Paris prosecutor's office described him as "psychologically unstable but conscious (of his actions) and determined".

The arrest took place on Thursday and the man was charged on Saturday for individual terrorist activity and remanded in custody, The prosecutor's office said that the suspect's plans were vague and not yet finalised, and that he appeared to be acting alone.

He did, however, tell police of a possible plan to attack Macron on July 14, when the French president traditionally attends the annual military Bastille Day military parade on the Champs-Elyées, and expressed "nationalist" views.

According to RMC, he said he wanted to make a "political" statement by killing Mr Macron, and said he wanted to attack "blacks, Arabs Jews and homosexuals".