The International Criminal Court (ICC) has convicted the former head of the Islamic police in Mali's historic city of Timbuktu for war crimes and crimes against humanity.

Prosecutors say al-Hassan ag Abdoul Aziz ag Mohamed ag Mahmoud led a "reign of terror" in Timbuktu after it was overrun in 2012 by the al-Qaeda-linked Ansar Dine group.

Hassan, who remained emotionless as the verdict was read out in the Dutch city of The Hague, was acquitted on charges linked to rape, sexual slavery and imposing forced marriages on women.

Judges also found he played no role in the destruction of ancient mausoleums in Timbuktu.

Hassan was handed over to the ICC in 2018 by the Malian authorities - five years after French troops helped liberate Timbuktu from the jihadists.

Ansar Dine was one of several Islamist militant groups to exploit an ethnic Tuareg uprising to take over cities in northern Mali.

In his role as police chief, Hassan oversaw punishments such as public amputations and the flogging of residents of the city, including children.

"Al Hassan has been found guilty by majority decision of war crimes and crimes against humanity, including torture, cruel treatment and outrages upon personal dignity, for the public flogging of 13 members of the population [of Timbuktu]," judge Antoine Kesia-Mbe Mindua was quoted as saying by the Reuters news agency.

"The inhabitants had no other choice but to adapt their lives and lifestyles to conform to the interpretation of Islamic Sharia law... imposed on them by the force of arms," AFP quoted the judge as saying.

He was also involved in interrogations where torture was used to extract confessions, the judge said.

The prosecution case included testimony from Dédéou Maiga that he was accused of petty theft and arrested by Hassan. He was then tied to a chair in public and his hand was amputated. Maiga died in 2017.

The International Federation for Human Rights (FIDH) welcomed the judgment in a statement, but expressed disappointment at the fact that Hassan was acquitted of the gender-based crimes.

FIDH secretary general Drissa Traoré said: "This verdict represents an important step for the victims in their quest for justice in relation to international crimes committed in Mali in 2012."

One survivor told FIDH they were dismayed at the outcome.

"I am partly disappointed by this verdict which does not take into account the rapes, let alone the sexual slavery, the suffering that I and other women in Timbuktu have suffered with the complicity of Al Hassan," she said.

Another Islamist militant leader who destroyed ancient shrines in Timbuktu was sentenced to nine years in jail in 2016.

Ahmad al-Faqi al-Mahdi admitted to leading rebel forces who destroyed historic mausoleums at the world heritage site in Mali in 2012.

Timbuktu was a major centre of Islamic learning between the 13th and 17th Centuries and was added to the Unesco world heritage list in 1988.