Online abuse is driving girls to quit social media platforms including Facebook, Instagram and Twitter, with nearly 60 percent experiencing harassment, a global study showed on Sunday.

One in five girls and young women has abandoned or cut down on using a social media platform after being targeted, with some saying harassment started when they were as young as eight, the survey by girls' rights group Plan International showed.

"Girls are being silenced by a toxic level of harassment," said the organization's chief executive, Anne-Birgitte Albrectsen.