Syrian activist and her 22-year-old daughter found murdered in Istanbul.

Syrian opposition activist Orouba Barakat and her journalist daughter were found murdered in their apartment in Istanbul last night.

The Istanbul police department said on Friday that bodies of 60-year-old Barakat and her 22-year-old daughter Halla were found overnight in their apartment in Istanbul's Üsküdar district in the Asian side of the city.

Turkish media reports said Orouba Barakat was investigating alleged torture in prisons run by the Assad regime. It said she had initially lived in Britain, then the United Arab Emirates before coming to Istanbul.

"The hand of tyranny and injustice assassinated my sister Doctor Orouba and her daughter Halla in their apartment in Istanbul," Orouba's sister Shaza wrote on Facebook, adding that they were stabbed to death.

"Orouba wrote headlines in the first page and she pursued criminals and exposed them. Her name and her daughter's name, Hala, now made first page headlines," Shaza added.

According to Syrian opposition activists, Arouba was a member of the Syrian National Council. She had backed the uprising against the Assad regime but also criticized some arms of the opposition.