Carl Michael von Hausswolff claims he used ashes he took from a crematorium at the Majdanek concentration camp in 1989, mixing them with water to create the painting entitled "Memory Works".
The monochrome work, featuring vertical brushstrokes in a rectangle representing the suffering of the victims, is on display at the Martin Bryder Gallery in the southern Swedish town of Lund.
A member of the public filed a police complaint against von Hausswolff on December 5 for "disturbing the peace of the dead", calling the artwork a "desecration of human remains", said police inspector Annika Johansson.
She said the police complaint was "very unusual", noting that von Hausswolff took the ashes in Poland, not in Sweden. It was unclear if using the ashes was considered a crime in the Scandinavian country.
Police said the prosecutor's office would investigate the case and decide whether to press charges.
Gallery owner Martin Bryder refused to comment on the work when contacted, and said the artist was also unavailable.
On the gallery's website, von Hausswolff explained that he travelled to Poland in 1989 for an exhibit and while there visited the Majdanek concentration camp.
"I collected some ashes from one of the crematoriums but didn't use it for the exhibit -- the material was too emotionally charged with the cruelties that had taken place there," he said.
"In 2010 I pulled out the jar of ashes and decided to 'do something' with it. I took out a few sheets of watercolour paper and decided to cover just a rectangular space with ashes mixed with water.
"When I stepped back and looked at the pictures, they 'spoke' to me: figures appeared... as if the ashes contained energy or memories or 'souls' from people... people tortured, tormented and murdered by other people in one of the most ruthless wars of the 20th century."
Swedish author and doctor Salomon Schulman condemned the exhibit as "offensive".
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"I'm never going to step foot inside this gallery to view this desecration of Jewish bodies. Who knows -- maybe some of the ashes come from some of my relatives," he wrote in a debate article in regional daily Sydsvenskan.
The gallery's website said the exhibit could only be visited by appointment.