VIENNA (AP) ― Naked men of all sizes and shapes are appearing on Vienna kiosks as a prestigious museum kicks off an exhibit of male nudity.

But outside the exhibition, organizers are being forced into cover-up mode after a storm of complaints that the ad posters are offensive.

In a show titled “Nude Men from 1800 to Today,’’ the Leopold Museum opened its doors Friday to examine how artists have dealt with the theme of male nudity over the centuries.

“Mr. Big’’ ― a four-meter high full-frontal photo mounted on plywood and depicting a naked young man in an indolent sprawl ― is set up near the show’s entrance, lest there be any doubt what visitors are about to see.

Inside, around 300 art works are on display ― including the controversial photograph that is raising the ire of Viennese. Created by French artists Pierre & Gilles, “Vive La France’’ shows three young, athletic men of different races wearing nothing but blue, white and red socks and soccer shoes.

No visitors were complaining Friday as they filed past that photo and even more graphic examples of male nudity, including some depicted in sex acts.

“I’ve seen worse on late-night TV,’’ said Franz Steiner, 27, as he left the show.

Not so in the city. Posters of the three men were given impromptu fig-leafs ― lines of red tape covering their private parts.

The complaints clearly caught the museum by surprise. Vienna’s turn-of-the-century decadence allowed erotic artists such as Egon Schiele and Gustav Klimt to flourish, and has turned these days into complacent acceptance of displays of the flesh. Today, lingerie ads are racy and one popular daily paper regularly features pictures of half-naked women.

Vienna’s public transport system reacted laconically earlier this week to reports that a young woman on a downtown subway line was dressed in nothing but knee-high boots.

“We know that everyone has a different temperature comfort zone,’’ the agency said in a statement. “But we do not think that our subways are so warm that one has to get undressed.’’

But there seems to be less tolerance for shows of male nudity. Museum officials say they received a flood of complaints by last week, mostly from outlying districts heavily populated by new immigrants from Muslim countries.

Museum director Tobias Natter says the flap serves to point out “that nobody gets offended by naked women, but with naked men: yes.’’

A poster near a school was also removed when parents complained.

“I can understand women with children who think that this is too wild, when the kids keep asking questions,’’ said Susanne Eigner, a woman her 20s standing next to a still-uncovered poster.

But other reactions were positive.

“I like that we get to see naked men for a change,’’ said Veronika Kren, as she paused from pushing her bike laden with groceries. “We have to look at naked women all the time and now I find it quite interesting to see something different ― and especially the reaction of the men.’’

The museum is making the most of the controversy. Natter says he hopes the poster will spark lively debate.

“Some people will say, ‘What a shame. I want to see what’s under that,’’’ he said about the red tape. “Others will say, ‘Let’s go the museum. There we can see the original.’ And some will say, ‘That’s good. I don’t want to see that in the public space.’