Eighty per cent of adolescents have accessed pornography online, with a fifth making their first visit by the age of 10, a survey has found.
The average age at which respondents first downloaded internet porn was 11.9, with most doing so at home.
The findings prompted an expert to call for a comprehensive review of sex education.
Some 43.2 per cent of respondents said they gained access to sexual content through pop-up adverts. Salacious online forums, chat rooms and comic websites were also common ways to view such material.
The findings show that 86.4 per cent of adolescents visit pornographic websites at home.
Chung Kim-wah, an assistant professor in the department of applied social sciences at Polytechnic University who led the research, said private computers increased privacy and the likelihood of users accessing online pornography.
Some 18.9 per cent of the youngsters looked at porn online for entertainment, 14 per cent used it to learn about sex, while 10.7 per cent said it satisfied their sexual needs.