During the event at Washington's Capital One Arena, Musk's enthusiasm for the prospect of sending an American to Mars led to a gesture that many have interpreted as being similar to the one by the Nazi forces of German dictator Adolf Hitler.

Campaigners from the German group the Center for Political Beauty and British activists Led by Donkeys shared pictures and footage online of the protest action they said they had staged late Wednesday.

The group projected the word "heil" in front of the Tesla logo, to spell out the message "Heil Tesla".

In comments to AFP, Philipp Ruch, founder of the Center for Political Beauty, said that Musk had given "a Hitler salute, just like American neo-Nazis have been practising for years".

In the aftermath of the incident, Musk took to his Twitter account to adamantly deny the claims, referring to it as no more than "dirty tricks" and "propaganda".

The controversy has sparked a heated debate among Tesla owners online, on platforms like Reddit, where customers are disappointed by the incident.

Some expressed a desire to sell their vehicles out of embarrassment, while others feel "stuck" with their cars.