Swedish police on Wednesday said they were investigating a hate crime after an unidentified person dumped a dead boar outside a mosque in southern Sweden overnight.

Police wrote on their website that the mosque "had a pig thrown at its facade".

"The complaint is being classified as agitation against an ethnic group, but other suspicions may arise later," police said.

The head of the foundation that runs the mosque in Skovde, Smajo Sahat, told AFP that it was later established that the dead animal was a wild boar.

"I came this morning and saw it, it was dead," he said. "A person came in a car and threw it at the mosque. We don't know who it was but it was caught on surveillance cameras," he added.

Sahat said there had been no recent threats against the mosque, which opened a year ago. "When it comes to why someone would do this, we can only speculate," he said.

The mosque has about 1,000 members, according to Sahat.