Militants with the Islamic State (IS) group have publicly killed a rights lawyer in the Iraqi city of Mosul after finding her guilty of apostasy in a self-styled Islamic court, the UN said.
The UN Assistance Mission in Iraq said Samira Salih al-Nuaimi was taken from her home on September 17 after allegedly posting messages on Facebook that were critical of the militants' destruction of places of worship in Iraq's second largest city.
The Gulf Centre for Human Rights said Ms al-Nuaimi had worked on detainee rights and poverty.
The extremist IS group seized Mosul in June during its rapid advance across the country's north and west. It has imposed a harsh version of Islamic law in areas under its control in Iraq and Syria.
Ms al-Nuaimi's Facebook page appears to have been removed since her death.
According to the UN Assistance Mission she was tried in a sharia court for apostasy, after which she was tortured for five days before the militants - also known as Isis or Isil - sentenced her to public execution.
"By torturing and executing a female human rights lawyer and activist defending in particular the civil and human rights of her fellow citizens in Mosul, Isil continues to attest to its infamous nature, combining hatred, nihilism and savagery, as well as its total disregard of human decency," Nickolay Mladenov, the UN envoy to Iraq, said.
In the once-diverse city of Mosul the group has forced religious minorities to convert to Islam, pay special taxes or die, causing tens of thousands to flee. The militants have enforced a strict dress code on women, going so far as to veil the faces of female mannequins in shop windows.
Last month, the group destroyed a number of historic landmarks in the town, including several mosques and shrines, claiming they promote apostasy.
The Gulf Centre for Human Rights said the killing was "solely motivated by her peaceful and legitimate human rights work, in particular defending the civil and human rights of her fellow citizens in Mosul".
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