A teacher in southern France has received a death threat containing a photo of Samuel Paty, prosecutors say.

       Two French teachers in the region of Aix-en-Provence have been sent threatening letters, the public prosecutor's office said on Monday.

       One of the letters contained an image of Paty, who was beheaded last year outside his Paris school by an 18-year-old Chechen refugee.

       The suspect said the attack on the 47-year-old history and geography teacher was revenge for Paty showing his class cartoons of the Prophet Mohammed, during a lesson on freedom of expression.

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       "In September, a couple of teachers received a photo of Samuel Paty in the mail, followed by a letter threatening their lives," said Dominique Laurens, the Marseille prosecutor.

       The matter is now being investigated by the regional division of France's public security directorate, she added.

       "The investigation is ongoing and at this stage, there is no evidence to link these facts to a course given by one of the teachers," Laurens told AFP.