Students at a Wisconsin high school have been left outraged after 'sexist' prom posters appeared on the school’s walls the week before the event, suggesting that the night should be seen as an opportunity 'to protect her character'.

The posters, which were put up on the walls of Lincoln High School in Manitowoc, depict the silhouette of a woman wearing a gown which is made up of words such as 'charming', 'fearless' and 'ambitious', while a banner printed above her head reads: ‘A night to protect her character.’

'It's basically just saying your character depends on whether or not you have sex,' senior Kelsey Schindl told Mashable. 'And if you have sex, you won't have any character.'

The message: The posters appeared around Lincoln High School in Manitowoc, Wisconsin, ahead of prom night, causing outrage among students because of its 'sexist' message

Despite being a public school, the posters distributed around Lincoln High bear the logo of The Crossing of Manitowoc County, a Christian-based pro-life pregnancy, and counselling service and the Holy Family Memorial, a Christian healthcare provider network in the area. The poster also appears to be signed by school principal Luke Valitchka.

Approved: Principal Luke Valitchka appears to have signed the bottom of the poster

After spotting the poster and tearing it off the wall, an incensed Kelsey marched to the principal's office to explain her opposition to the message. She expressed her belief that the posters 'sex shame' girls and imply that their sexuality directly affects their character.

Kelsey offered to create her own posters for the school that rather promoted 'acceptance'. But the principal reportedly disagreed with her interpretation and insisted the original posters remain.

'I wanted to post a message that said you are no less of a person if you have sex and your character does not depend on your virginity,' she told HTR News. 'I'm not endorsing teens to have sex, but you're not a bad person if you do and you're not a bad person if you don't.'

Since then, Kelsey has started a campaign in her school, even creating a petition against the posters and their message. She found soon enough that she was not alone in her opinion.

'Just about everyone I've talked to sees just how messed up that poster really is and [the principal] should know the effect it has and how people feel,' Kelsey explained to Mashable. 'It's not just my opinion.'

The poster is gaining attention nationwide now after Kelsey's older brother posted the image to Reddit, writing: 'My sister came home absolutely livid at the sight of a set of posters her school had been putting out.' He added that she had also been in contact with school officials and local papers.

Some comments in the thread from former students at the school point out that 'Manitowoc is heavily evangelical protestant and catholic' while others shared in the student's outrage, with one saying: 'It really freaks me out the obsession with a girl's virginity. Good on your sister for doing something about it. I love how no one ever says anything about protecting the boy's virtue.'

The post also gained the attention of blogger Hemant Mehta, also known as The Friendly Atheist, who called the posters 'illegal', adding: 'Public schools are simply not allowed to post church-sponsored material on the walls. While student groups could advertise a Bible Club meeting, outside churches can’t push their beliefs on the students.'

A public school scandal: Lincoln High School's prom is due to take place this Saturday

In a statement to Mashable, Holy Family Memorial said that it 'supports the core message within this Prom poster, which is the promotion of social responsibility and safe behaviors for both young women and men'.

'This poster was one part in a series of timely social messages reinforcing the importance of values such as confidence, honesty and determination. We firmly support the message of promoting healthy and responsible behavior among the youth of our community,' a spokesperson added.

A statement from the Manitowoc Public School District denied that the nature of the poster was religious, saying: 'This poster was one of several merely intending to promote a positive prom experience. No particular religious standard or expectation was being promoted.