It claims to be California's "fastest growing political party," boasting nearly half a million members.

Dubbed the American Independent Party (AIP), the ultra-conservative group is staunchly opposed to abortion rights, same sex marriage and says it wants to erect a giant fence across the entire country's border.

But an investigation by an American newspaper has revealed that as many as 70% of its members - including left-wing Hollywood stars Demi Moore and Emma Stone - joined the party by accident.

Tens of thousands of voters were confused by the use of the word "independent" on the registration forms, according to the LA Times.

It meant that many voters ticked the "American Independent Party" box on their registration forms because they mistakenly thought it meant politically neutral.