Image copyright Getty Images Image caption Wonder Woman's appointment was criticised by UN staff and women's rights advocates

The UN has ended its campaign with comic book heroine Wonder Woman, a spokesman says, less than two months after her appointment sparked outrage.

The superhero had been declared an honorary ambassador to promote messages about women's empowerment and gender-based violence.

The character's "sexualised" appearance was one element critics seized on to deem the choice inappropriate.

A petition against the selection gathered nearly 45,000 signatures.

The UN did not explain why the project with Wonder Woman, announced in October, would end on Friday.

But spokesman Jeffrey Brez said campaigns using fictional characters often lasted no longer than a few months, Reuters news agency reported.

DC Entertainment, which publishes DC Comics, said it was pleased with the exposure Wonder Woman had brought to the cause.

Warner Bros and DC Entertainment are supporting a year-long campaign by the UN and its children's agency, Unicef, for gender equality and women's empowerment.

Image copyright AP Image caption UN employees turn their backs during the announcement of Wonder Woman's role

In the petition against the character's appointment, opponents said the image she projected was "not culturally encompassing or sensitive".

"It is alarming that the United Nations would consider using a character with an overtly sexualised image at a time when the headline news in United States and the world is the objectification of women and girls," it said.

Wonder Woman - an Amazonian from the all-female paradise of Themyscira - masquerades as Diana Prince, whose occupations include an army nurse, until her services are called on by a society in peril.

She first came to the public's attention in October 1941, and was most famously played by actress Lynda Carter in the hit US TV series that ran from 1975-79.

The announcement came as the UN itself was under criticism for having a lack of gender parity in senior roles.

Despite campaigns there has never been a female secretary general and one analysis found that in 2015 nine of 10 senior leadership jobs went to men.