One person has already been arrested and police are looking at whether they were helped by several others to organize the transportation of asylum seekers using mini buses and rental cars between August and November 2014.
"I can say that this is the largest smuggling investigation in our country for many years, but I cannot say much more than that right now in case it jeopardizes the case," Patrick Engström, chief of the border police section of the Swedish National Police Board, told The Local on Thursday.
He confirmed that regional police in Stockholm were working on the case, although he added that did not necessarily mean that the suspects came from Sweden's capital.
"It is a question of resources. All I can say is that police in Stockholm are managing the investigation."
According to Swedish broadcaster SVT, at least one smuggler was arrested in early March.
It reports that two of the suspects being investigated by police have Swedish citizenship, one Spanish and another comes from Syria. All deny any criminal actions, the network understands.
The maximum penalty for organizing people smuggling to Sweden is six years in prison.
Isabelle Bjursten told SVT that the suspects are not presently thought to be connected to any migrant boat organizations in Sicily.
"We are wondering how the smugglers could have got in contact with refugees in Italy. But at present there is no evidence to suggest that there are links with a smuggling network in Sicily. Our investigation involves transportation within Europe," she said.
The Local has contacted Bjursten for comment.