An influential Malian judge with links to Al-Qaeda has said some schools in the country cannot reopen unless boys and girls are kept apart and wear Islamic dress, according to a letter verified by AFP on Thursday.

The letter, addressed to the governor of Timbuktu, also calls on school authorities to introduce Arabic and the study of the Koran.

Half a million children in Mali have been affected by 1,766 school closures, UNICEF said in October.

Jihadist groups say the Malian education system fails to respect the regulations they advocate by allowing boys and girls to mix, using French, and permitting dress considered contrary to their rules.

The judge, Houka Houka Ag Alhoussein, set out the three conditions for the reopening of schools, in areas under jihadist influence, in his letter dated October 26 and authenticated to AFP by a source within the governorate.

Ag Alhousseini is a former Islamic judge during the 2012 jihadist occupation of Timbuktu and is on the UN sanctions list. Officially a teacher, he is also a moral and religious authority through his rank as cadi, or Islamic court judge.

His letter deemed it "necessary" that "the rows of girls and boys be separated by a barrier when it is not possible to separate the class". The teacher should also be of the same sex as the pupils, he said.

Students should dress "decently as required by the Muslim religion", while on their way to school, he added.

In a report on human rights violations in Mali seen Thursday by AFP, the UN said the jihadist fighters are "imposing" their "rigorous interpretation of the precepts of Islam as well as the forced payment of zakat", the Islamic tax, on the local population in Timbuktu.

It said that in early July, seven women who were not wearing black veils in Duekira, in the Timbuktu region, were whipped by fighters under the banner of the Al-Qaeda-linked Jama'at Nasr al Islam wal Muslimin (JNIM), led by Iyad Ag Ghali.