A woman has been arrested on suspicion of offending religious sentiment, after posters bearing an image of the Virgin Mary with her halo painted in the colours of the rainbow flag appeared in the city of Płock in central Poland.

The Polish interior minister, Joachim Brudziński, announced on Twitter on Monday that a person had been arrested for “carrying out a profanation of the Virgin Mary of Częstochowa”.

A Płock police spokeswoman confirmed a 51-year-old woman had been arrested over the alleged offence. The woman had been abroad, but upon her return, the police entered and searched her home, where they found several dozen images of the Virgin Mary with the rainbow-coloured halo.

The “Black Madonna of Częstochowa” is a revered Byzantine icon that resides in the monastery of Jasna Góra, a UN world heritage site and Poland’s holiest Catholic shrine.

Offending religious feeling is a crime under the Polish penal code. If convicted, the woman could face a prison sentence of up to two years.

Brudziński, who described the posters as “cultural barbarism” when they appeared overnight in April, said: “Telling stories about freedom and ‘tolerance’ doesn’t give anyone the right to offend the feelings of believers.”

Poland’s ruling rightwing Law and Justice party (PiS) has sought to mobilise its core electorate in the run-up to the European elections by raising the spectre of the country being overwhelmed by western liberal social values.

“We are dealing with a direct attack on the family and children – the sexualization of children, that entire LBGT movement, gender,” said the PiS leader, Jarosław Kaczyński, speaking to supporters last month. “This is imported, but they today actually threaten our identity, our nation, its continuation and therefore the Polish state.”