An online poll has found that one in five young people has been harassed or bullied via the internet.

The national youth poll by Democrats Senator Natasha Stott-Despoja has surveyed young people aged 15 to 20 in all states and territories.

Most respondents used the internet regularly, with 22 per cent saying they had been a victim of some form of bullying.

Body image was a major concern for more than half of those surveyed and 58 per cent supported same-sex marriages.

The poll found almost half knew a young person who had attempted or committed suicide.

Tags: bullying, cyber-bullying, suicide, teen