A Mauritanian secondary school student has been arrested for writing an exam paper considered insulting to the Prophet Muhammad in last month's baccalaureate exams.

Domestic media have reported that religious authorities demanded the death penalty if the young woman, who has not been named, is found guilty of blasphemy in court.

Mauritania has strengthened blasphemy laws, prescribing the death penalty for Muslims who "ridicule or insult God or the Prophet, even if they repent".

Previously people could avoid the death sentence if they expressed remorse.

Pan-Arab news outlet al-Quds al-Araby reported on Wednesday that the student is from the north-western town of Atar and comes from the Haratin ethnic group, who are the descendants of slaves of sub-Saharan origin.