France's Interior Minister Gerald Darmanin has slammed "unacceptable acts" against the Muslim community after a boar head was found near a mosque in the east of the country.

A prosecutor said a probe into "incitement to racial hatred" had been opened after worshippers at a mosque in the village of Contrexeville in the Vosges region discovered the animal's head on Friday.

Darmanin late Saturday said that two other mosques in northern France had also been "degraded".

"This weekend mosques in Valenciennes and Fresnes-sur-Escaut were degraded. A mosque in the Vosges was also targeted. I firmly condemn these unacceptable acts against our Muslim compatriots," he said on X, formerly Twitter.

The incidents come during the Islamic holy month of Ramadan, during which believers fast from dawn till dusk and focus on prayers.