“People have to be extremely watchful about this,” Nils Norling from the Malmö Police told the Sydsvenskan newspaper.
“Normally, you can see something about the note that doesn't look right. It doesn't have the same vibrance, or feels different from a normal note.”
According to Malmö police, there have been 22 cases of fraud or attempted fraud using counterfeit currency in the first few weeks of this year. And in the nearby city of Lund, there were two similar frauds over the weekend in which people bought mobile phones secondhand using counterfeit notes.
“Police suspect that more people may have been affected and that more are going to be affected because the buyers with counterfeit notes appeared to be in possession of more counterfeit notes than those they paid with,” Calle Persson, a police spokesperson, wrote in a statement published on Monday.
According to Persson, the two victims had met buyers in person and taken payment in 500 kronor notes. They only discovered later that the notes were counterfeit.
The current 500 kronor note, which features the opera singer Birgit Nilsson, was introduced in 2016.
It has fibres spread across the note, which fluoresce under ultraviolet light, as well as a UV image of three crowns, a colour shifting image, a security thread, a security, a watermark, and intaglio print, all of which make printing a convincing counterfeit challenging.
There were a total of 69 reports of counterfeit currency being used last year.
In October last year, police in Malmö warned that fast food restaurants had reported customers attempting paying with fake 500 kronor notes. And in June, a supermarket reported three men for defrauding it of 3,000 kronor, after they visited it three times in the same day, each time making small purchases with fake 500 kronor notes and pocketing the change.