The Oresund, the 2.5-mile stretch of water which connects the Baltic Sea to the Atlantic Ocean and separates the two countries, isn't enough to keep the animals from entering Sweden, wildlife officials said.
"They're good swimmers," wildlife officer Bertil Nilsson told The Local Tuesday.
The raccoons are a threat because of rabies, tapeworm and their destructive potential in wetlands, he said.
"In Finland the large wetlands areas are all but emptied of ground-nesting birds and frogs," Nilsson said.
Authorities said cameras are in place along the Oresund to monitor the threat.
"It's really very serious, they're spreading very quickly in Denmark," Nilsson said.
Raccoons are not indigenous to northern Europe and are considered an invasive species.
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