In January, police in the Swedish capital stopped 716 people to perform an "internal border control", but only 42 people proved to be in the county without residency rights, the Metro newspaper reported.
Statistics for the months of December and February are characterized by a similar margin of error of around 90 percent.
"That's a high margin of error," Sören Clerton, head of the border control division of Sweden' National Bureau of Investigation (Rikskriminalpolisen, NBI) told the newspaper.
"That's a figure that should be as low as possible."
Clerton admitted it was impossible for police to guarantee that no one be stopped because of their appearance or language. He promised that police would review their procedures to see if there was anything wrong with their methods.
Simon Andersson, a PhD candidate in legal procedure, criticized the police's high margin of error.
"You need a very strong reason to believe someone doesn't have the right to be here," he told Metro
"The Swedish people don't want people stopped for looking foreign, and it's very strange to use another pretence, like fare-skipping, to stop people."