A mosque in Vernon, northern France received a threatening letter Tuesday, according to a Twitter post by the Islam & Info website.
The notice, left in the mosque's mailbox, contained death threats and insulting messages against Turks, Arabs and the community who comes to the mosque regularly.
"The war has begun. We will drive you out of our country. You will give account for Samuel's death," it said.
It was referring to Samuel Paty, a teacher at Bois-d'Aulne College in Conflans-Sainte-Honorine who was beheaded on Oct. 16 by Abdullakh Anzorov, an 18-year-old of Chechen origin, for showing controversial cartoons of Prophet Muhammad to his students during one of his classes on freedom of expression.
The notice also contained ugly remarks directed against Muslim women wearing headscarves.
The Grand Mosque of Pantin outside Paris was recently closed for six months after it shared a video on its Facebook page criticizing Paty, before his murder.
Earlier this month, President Emmanuel Macron accused French Muslims of "separatism" and described Islam as "a religion in crisis all over the world."
Tensions further escalated after Paty's murder. Macron paid tribute to him and said France would "not give up our cartoons."
Insulting cartoons by Charlie Hebdo, a French satirical weekly magazine, were also projected on government buildings in a few cities.
Several Arab countries, as well as Turkey, Iran and Pakistan, have censured Macron's attitude toward Muslims and Islam. Turkish President Recep Tayyip Erdoğan said the French leader needs "mental treatment."
While calls to boycott French products are circulating online in many countries, Erdoğan has urged Turks "to never buy French brands."