STOCKHOLM (AFP) - Assailants threw pig's trotters into a mosque near Stockholm after smashing the windows of its main door, police said on Monday.

"Shortly before 11.00 am, we received a call from the mosque" in Fittja, police official Ulf Lindgren told AFP. "The person had just arrived and found pig's trotters inside."

In Islam, pork meat is considered impure.

"We have classified this as an act of vandalism," the official said. "But insofar as it is pig's trotters, it could be something else."

Police are looking for witnesses in the area and have no suspects so far.

"In Sweden, pig's trotters are a traditional dish around Christmastime. You can buy them easily," officer Lindgren said.