Two trainers -- from Germany and Sweden -- were also arrested in the raid on a digital security workshop run by Amnesty at a hotel in Buyukada, reports the BBC.
The police raid was "blatantly without cause", an Amnesty statement said.
The activists' whereabouts were yet not known.
The police action "is a grotesque abuse of power and highlights the precarious situation facing human rights activists in the country", said Salil Shetty, Amnesty International's Secretary General.
"Idil Eser and those detained with her must be immediately and unconditionally released," the BBC quoted Shetty as saying.
Police have jailed more than 50,000 people across Turkey since a coup plot a year ago.
(This story has not been edited by Social News XYZ staff and is auto-generated from a syndicated feed.)
About VDC
Doraiah Chowdary Vundavally is a Software engineer at VTech . He is the news editor of SocialNews.XYZ and Freelance writer-contributes Telugu and English Columns on Films, Politics, and Gossips. He is the primary contributor for South Cinema Section of SocialNews.XYZ. His mission is to help to develop SocialNews.XYZ into a News website that has no bias or judgement towards any.