Turkey's state-run news agency says a Syrian activist and her journalist daughter have been killed in their home in Istanbul.

Anadolu Agency said the bodies of 60-year-old Arouba Barakat and 22-year-old Hala Barakat were discovered late Thursday after friends worried about the journalist, who hadn't showed up for work, alerted police.

There has been a string of attacks against activists in Turkey. The Islamic State group has claimed the killings of four Syrian journalists in Turkey.

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

Her daughter was a journalist working for the opposition's Orient news.

Anadolu said the women were stabbed.