Rights groups and government critics in Poland are protesting Tuesday after police temporarily detained a human rights activist for putting up posters depicting the country’s most revered Catholic icon with the LGBT rainbow on the halos of Mary and baby Jesus.

Prosecutors in the central city of Plock said the activist, 51-year-old Elzbieta Podlesna, has been questioned and has heard charges of insulting religious feelings and desecration of the icon of Mother of God of Czestochowa, popularly known as the Black Madonna of Czestochowa, a painting housed at the Jasna Gora monastery in Czestochowa, in southern Poland, since the 14th-century.

Last month, Podlesna placed posters with altered images of the icon on walls, garbage bins and mobile toilets near St. Dominik’s church in Plock. She did not physically damage the icon, which was venerated by pontiffs including Pope John Paul II. Jasna Gora is the nation’s holiest shrine, drawing hundreds of thousands in annual pilgrimages. The late Pope John Paul II, who was Polish-born, visited it since childhood and as a clandestine student during WWII.

About 300 people with a giant rainbow flag and holding posters of the altered icon heard speeches from human rights activists as they staged a peaceful protest in downtown Warsaw. Earlier Tuesday, European Council president Donald Tusk, who was in his native Poland, said the Polish authorities’ harsh reaction was “inconceivable.” The Warsaw-based Helsinki Foundation of Human Rights found the raid on Podlesna’s home and her brief detention “hard to understand.” Read more via Time