After years of declaring he stood for "truth, justice and the American way," Superman has provoked the ire of rightwingers by threatening to renounce his US citizenship.

In the latest issue of Action Comics, which went on sale on Wednesday, the Man of Steel decides to take the step after he intervenes in a protest against the Iranian government.

After the Islamic regime brands his non-violent protest as an act of war taken on behalf of the US president, the DC comic hero says he will renounce his citizenship before the United Nations.

"I'm tired of having my actions construed as instruments of US policy," he says.

Although Superman never actually renounces his citizenship in the story, conservative commentators reacted with disgust.

In a blogpost at The Weekly Standard, senior writer Jonathan Last questioned Superman's beliefs, now that he seems to have rejected the United States. "Does he believe in British interventionism or Swiss neutrality?" Last wrote. "You see where I'm going with this: If Superman doesn't believe in America, then he doesn't believe in anything."

Posters on comic book discussion forums drew parallels between the superhero's doubts about his citizenship and the conspiracy theories about Barack Obama's nationality.

Several posters branded conservative critics of the storyline "Earthers" - a reference to the Birthers - the nickname for the rightwingers who have questioned Obama's citizenship.

The plot comes as the superhero from the planet Krypton, who was raised by a Kansas farmer and his wife, looks to take on a more global mission for his battle against injustice. "The world's too small. Too connected," Superman says.

Superman, who was first introduced in 1938, has a long association with the United States, although Joe Shuster, the artist who helped create the character with writer Jerry Siegel, was born in Canada.

Superman's life story of assimilating into US culture has been seen as a metaphor for the immigrant experience, particularly Jewish immigrants.

DC Comics co-publishers Jim Lee and Dan DiDio appeared to downplay their character's declaration in a joint statement.

"In a short story in Action Comics 900, Superman announces his intention to put a global focus on his never ending battle, but he remains, as always, committed to his adopted home and his roots as a Kansas farm boy from Smallville," they said.

In a story published in 1974 Superman was granted citizenship of every member country of the United Nations.