French police launched an investigation on Tuesday after pig heads were found outside several mosques in the Paris region, the city’s police chief said.

At least nine were found, Laurent Nunez said, adding more could still be discovered.

“Pig heads have been left in front of certain mosques … four in Paris and five in the inner suburbs,” Nunez told a press conference. He said police weren’t “ruling out the possibility that others may be found.”

Nunez said in a post on X that “every effort is being made to find the perpetrators of these despicable acts.”

The heads were discovered on public roads in Paris and three nearby suburbs, according to local authorities.

Interior Minister Bruno Retailleau condemned the acts, calling them “outrageous” and “absolutely unacceptable.”

“I want our Muslim compatriots to be able to practise their faith in peace,” he said.

Chems-Eddine Hafiz, the rector of the Grand Mosque of Paris, denounced the “Islamaphobic acts” as “a new and sad stage in the rise of anti-Muslim hatred” and called for “awareness and national solidarity against this dangerous trajectory.”

France is home to the largest Muslim community in the European Union, more than 6 million, as well as the largest Jewish population outside Israel and the United States. In Islam, eating pork is strictly forbidden because it’s considered impure.

Several European Union nations have reported a spike in “anti-Muslim hatred” and antisemitism since the Gaza war started in October 2023, according to the European Union Agency for Fundamental Rights.