A unknown virus has killed nearly 200 seals this summer, the newspaper The Local said Friday. Tests by British researchers were unable to find any indication the deaths were caused by seal plague, the newspaper Dagens Nyheter said.

Tero Harkonen from the Swedish Natural History Museum said the mystery virus may have crossed a species boundary and could be dangerous to humans.

"We do have our suspicions regarding the nature of the virus and are working to confirm these. But until then I wouldn't like to speculate as to how the infection spread to seals or the level of risk to other species," Harkonen told Dagens Nyheter.