At least nine pigs' heads were found outside several mosques in the Paris region on Tuesday, the city's police chief said -- an incident that has sparked alarm over rising anti-Muslim hatred.

"Pigs' heads have been left in front of certain mosques... Four in Paris and five in the inner suburbs," Laurent Nunez told a press conference, adding that officers were not "ruling out the possibility of finding more".

Police have opened a probe into incitement to hatred aggravated by racial or religious discrimination, Nunez said, calling the acts "despicable".

The consumption of pork is considered haram -- forbidden in Islam -- as the meat is believed to be impure.

Several of the heads had the surname of President Emmanuel Macron scrawled on them in blue ink, the Paris prosecutor's office told........

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