"There is concern that some 3,000 pigs have died in the flames. That is the information I have received from the police officers at the scene," said Mikael Erkki, duty officer at the police in Kronoberg and Kalmar on Sunday morning.
The fire began in the early hours of Sunday but was brought under control and extinguished during the morning.
"The fire is out now. Not all the buildings burned down, the fire was contained in the central buildings on the farm," said Juha Vierola at Kalmar emergency services.
Veterinarians will inspect the animals in due course and some uncertainty remained on Sunday afternoon as to just how many pigs succumbed to the flames.
The fire was called in to the emergency services at around 3.30am on Sunday. No people are reported to have been hurt in the flames.
"There were several buildings in flames and 3,000 pigs trapped in there," said Juha Vierola.
According to Kalmar police the estimate of the number of pigs housed in the building has since grown to around 5,000. The cause of the fire remained unknown, but the police are currently not entertaining suspicions of arson.