WARSAW (AFP)---Poland has asked Sweden to question three people over the theft of the "Arbeit macht frei" sign from the Nazi death camp at Auschwitz, Polish prosecutors said.   

"We are asking Swedish justice authorities to question three people, all of them Swedish citizens, in the presence of our prosecutors investigating the case," Krakow regional prosecutor spokesperson Boguslawa Marcinkowska told AFP.   

"The questioning is very important to the investigation," Marcinkowska said, but refused to reveal the identity of the persons to be questioned.   

Polish media reports say that a Swedish millionaire, identified only as Lars W., allegedly asked suspect Anders Hoegstroem to arrange the theft late last year of the infamous "Arbeit macht frei" sign.   

Last week Polish court remanded in custody until September 9 Hoegstroem, 34, a former leader of the Swedish extreme-right.   

He was extradited to Poland from Sweden in April and initially remanded for three months to give prosecutors probing December's theft more time to question him.   

Hoegstroem was arrested in his homeland on a Polish warrant in February. He risks 10 years in prison if convicted.   

Prosecutors have said Hoegstroem denies plotting the theft of the gateway sign from the site of the camp in the southern Polish city of Oswiecim, which has became a notorious symbol of genocide by the Nazis.   

Polish police recovered the five-metre (16-foot) metal sign -- which means "Work Will Set You Free" in German -- two days after it went missing.

They already arrested and charged five Polish men for the theft, three of whom, considered relatively small fry, have already been sentenced to two-and-a-half years in prison.   

The two others, suspected of playing a far more prominent role in the theft, are to be tried after Hoegstroem has been questioned.   

In 1994, Hoegstroem founded the National Socialist Front, a Swedish neo-Nazi movement he ran for five years before quitting.   

He has told Swedish media he was to act as an intermediary to pick up the sign and sell it to a buyer, adding however that he informed Polish police about the people behind the plot.