Högström, 34, was arrested on February 11 over the theft of the sign which disappeared on December 18th from over the gate of the notorious World War II camp set up in occupied Poland by Nazi Germany.
“The Stockholm court has taken the decision that he should be extradited to Poland and that he should remain in custody,” Agneta Hilding Qvarnström told AFP.
Högström has three weeks to appeal, and if unsuccessful “the authorities have to come and get him and they have 10 days to do so,” she added.
His lawyer, Björn Sandin, told Sweden’s TT news agency that he would advise Högström to appeal.
Högström has told Swedish media he was supposed to act as an intermediary to pick up the sign and sell it to a buyer, but in the end he wound up informing Polish police about the people behind the plot.
Högström in 1994 founded the National Socialist Front, a Swedish neo-Nazi movement he headed for five years before quitting.
Polish police recovered the five-metre (16-foot) metal sign, whose German inscription means “Work Will Set You Free”, on December 20, two days after the theft. They arrested and charged five Polish men.
The sign, which had been cut into three parts, was returned by investigators to the Auschwitz museum on January 21, less than a week before commemorations marking the 65th anniversary of the camp’s liberation by Soviet Russian troops.
The sign has long symbolised the horror of the camp where some 1.1 million people — one million of them Jews — were victims of Nazi German genocide from 1940 to 1945.