Officers say that the rogue police officers have asked some residents for personal information, such as bank card details, while on at least two occasions they have accused pensioners of having sex with a child.
The city’s police force has put a warning on its website, asking people to be aware of potential approaches from fake officers.
“It is serious and worrying,” Anders Olofsson, a spokesperson for Sweden’s National Fraud Centre, told Swedish newspaper Metro on Thursday.
He said he was especially worried about elderly people being duped, and said it was better for the public to become more suspicious by raising the issue, rather than failing to keep Swedes informed.
“It will become harder for us, but in general I do not think it will damage confidence,” he said.
According to Stockholm police, at least one resident was phoned up by a hoaxer who said that a plain clothes officer would be arriving to take a photo of their ATM card. When the resident asked to see identification, the ‘police officer’ offered to go and get it, but never came back.
“One should keep in mind to always request I.D,” added Olofsson.
“There are very few situations where police officers do not need to show I.D.”
He also advised people who received suspicious phone calls purporting to be from officers to ask for their names and to report them to the police switchboard if they were concerned.