A conservative lobby group says it wants an explicit T-shirt removed from public view before an exhibition featuring it opens at Canterbury Museum tomorrow.
Family First laid a complaint with police today about the item, which the museum intends to display in a restricted R-18 area.
The T-shirt, from the British heavy metal band Cradle of Filth, features a graphic image of a nun on the front and uses offensive language to describe Jesus Christ on the back.
It was banned by New Zealand's Chief Censor in 2008 for being degrading to women and Christians.
Family First director Bob McCoskrie said it was one of the worst T-shirts he had ever seen. If it involved other religions, the museum would not be as brave, he said.
"In terms of the Catholic Church, they have been an easy target and that's probably why they've allowed this shirt to go through.
"But I can guarantee there'd be some other special groups that probably they wouldn't be so confident about allowing, or be so brave about."
Eddie Zammit, who owns the shirt and others on display, said people needed to appreciate the art that went into T-shirt design.
"The exhibition is about proving that it's more than just a T-shirt. And I guess it comprises of a collection of T-shirts that I've collected for the last 20-plus years."