Photo: undated photo of sign over Auschwitz.
34-year-old Anders Hogstrom was detained in Stockholm on a European arrest warrant, a Swedish prosecutor said.
The infamous sign, which means "Work Sets You Free" in German, was stolen in December from the site of the Nazis' former Auschwitz death camp in Poland.
Polish police found it in the woods three days later cut up into three pieces and charged five Polish men with its theft.
Photo: Polish police unload part of the infamous "Arbeit Macht Frei" sign Monday Dec. 21, 2009.
Polish officials have said Hogstrom is suspected of incitement to commit theft of a cultural treasure.
The Polish prosecutor has said he has evidence that Hogstrom visited Auschwitz with two Poles last spring and told them to steal the sign.
Hogstrom will be appointed a defense lawyer and questioned by Swedish investigators before authorities can decide on extraditing him to Poland.
Photo: Part of the Auschwitz war crimes court inspects the former Nazi extermination center in Poland in Dec. 1964.
The Auschwitz sign is one of the most well-known slogans for Nazi Germany's atrocities during World War II and the Holocaust.
Between 1940 and 1945 more than 1 million people, mostly Jews, were killed in the gas chambers of Auschwitz-Birkenau or died of starvation or disease while forced to perform hard physical labor at the camp.