A survey by the Internet safety organisation Netsafe has found that about 25% of secondary school students have been aggressively sexually solicited online.
Netsafe executive director Martin Cocker told Nine to Noon that any child is at risk online if they are left exposed to more sophisticated adults.
Mr Cocker says teenagers who are sexually solicited over the Internet almost never go to their parents, or teachers.
He said there are no definitive warning signs to alert parents that children are being targeted and they must simply closely supervise their children's Internet activities. He says many parents fail to appreciate how dangerous the Internet can be.
Meanwhile, a new police unit is being formed to fight online sexual predators. Its spokesperson, Detective Senior Sergeant Neil Holden, said the unit will be able to work proactively to protect young Internet users rather than just reacting to complaints.
He said parents should be wary of allowing their children to surf the Internet unsupervised.